Gary Hooper's late goal secured a 1-0 SPL win for Celtic as Motherwell paid the price for missing a penalty at Parkhead.
Hoops keeper Fraser Forster made a brilliant save from Tom Hateley's penalty, awarded for Kelvin Wilson's challenge on Jamie Murphy, just before Hooper converted a Georgios Samaras cross from close range on 79 minutes.
Well keeper Darren Randolph kept Celtic at bay with a series of saves although there were some glaring misses too before Hooper pounced to take Neil Lennon's side into the winter break nine points clear of Inverness.
Samaras had the ball in the net from Kris Commons' cross in the second minute but was flagged offside. Commons then flashed a shot from the edge of the box just wide after being set up by Hooper.
In the seventh minute Darren Randolph made a fine save from Hooper's stab from close range after more good work on the left from Samaras, before tipping stand-in skipper Charlie Mulgrew's curling free-kick over the bar.
There was no let-up in the pressure on the Motherwell goal and moments later Randolph flew to his left to pluck a goal-bound Commons shot out of the air.
Jamie Murphy, skipper for the day, should have put the visitors ahead following a break in the 20th minute when he was played in by Keith Lasley but he lashed the ball over the bar.
In the 37th minute Murphy tested Forster with a drive from the edge of the box and moments later curled a shot from 14 yards past the far post.
With seconds remaining Efe Ambrose missed the chance of the half when Randolph dropped Wanyama's header from a Mulgrew corner, the Parkhead defender hooking the ball over the bar from barely two yards.
Celtic had an unconvincing start to the second period but with six minutes gone Randolph tipped a deflected shot from Wanyama over the bar.
Motherwell were handed a great chance to take the lead when referee Steven McLean adjudged Wilson to have tripped Murphy in the box. There was some concern as to whether Hateley had the ball on the spot or not - and Forster was booked for pointing this out - but when the Motherwell player blasted his shot to his left the Celtic flew across to make a great save.
The incident seemed to energise Celtic and they were soon in the lead when Hooper played the ball to Samaras and ran into the box to collect the return pass and slip the ball under Randolph from six yards.
There were some nervy moments before the final whistle as Motherwell went for broke but in the end Celtic deserved their win.
The 21-year-old midfielder has started every league game for Ronnie Moore's promotion-chasers this season after joining them in August, making 28 appearances.
Moore said: "I've been delighted with Liam this season. He has been a model professional while he has been here and a credit to Sheffield Wednesday.
"He's formed a great partnership with James Wallace and more recently Max Power in the centre of our midfield and has improved as the season has gone on.
"I think there's more to come from him too. He's not scored yet, but I think he has goals in his game.
"I'd like to thank Sheffield Wednesday and Dave Jones for allowing Liam to come back to us."
Fraser Forster made a brilliant save from Tom Hateley's penalty, awarded for Kelvin Wilson's challenge on Jamie Murphy, just before Hooper converted a Georgios Samaras cross from close range with 11 minutes remaining.
Not for the first time this season, though, the champions ended up struggling to get three points from a match that should have been over by the interval.
Darren Randolph kept Celtic at bay with a series of saves although there were some glaring misses too before Hooper pounced to take Neil Lennon's side into the winter break nine points clear of Inverness at the top of the table.
Elsewhere, Liam Craig grabbed the only goal of the game to hand St Johnstone a 1-0 victory as Dundee's survival hopes were dealt a further blow.
Nearest rivals Ross County's own match fell victim to the weather but the Dens Park side failed to edge closer to the Highland outfit.
Defeat means Dundee have claimed just one point from their last seven matches.
A Niall McGinn free-kick shortly after half-time spared the blushes of Jamie Langfield as Aberdeen and Dundee United battled out a 2-2 draw at Pittodrie.
The home side had taken an early lead through Scott Vernon, but Gavin Gunning turned home a leveller, and Langfield put through his own net to give the Arabs an unexpected half-time lead.
However, top scorer McGinn blasted a free-kick into the top corner to level the scores, and see that both sides began 2013 with a point.
St Mirren failed to clinch a second successive victory in the SPL as Cammy Bell helped Kilmarnock earn a hard-fought 1-1 draw at St Mirren Park.
Liam Kelly fired Kilmarnock ahead from the penalty spot after just four minutes when James Dayton was brought down inside the box.
St Mirren pushed for an equaliser and Bell made three fantastic saves before finally conceding to Paul McGowan's penalty midway through the second half.
There were late chances for Jim Goodwin and David Barron, but the Rugby Park side held out for a point.
Hibs responded from a four-match winless streak, including a dire performance in losing at home to Ross County, by beating Scottish Premier League leaders Celtic at Easter Road last Saturday.
Fenlon is looking forward to the chance for his players to show their quality at Tynecastle, at the home of their greatest rivals.
"We've been fantastic all season," he said.
"We didn't play to the level we felt we could against Ross County, but I don't think there's been loads of performances where we've been poor.
"It's going to be a tasty atmosphere and a decent game. I'm looking forward to it.
"Both the games we've played here have been fairly tight and close and some decent football.
"Hibs-Hearts is normally frantic and probably will be for a period. We feel we've got some players who can go in and play. That's what we've got to try to do.
"With the team we have we feel we can go there and cause them problems."
The third Edinburgh derby of the season comes amid suggestions of a change of fortunes of the capital clubs, with Hearts in deep financial turmoil and Hibs in the top half of the table after recent battles to avoid relegation.
Hibs are seeking another victory over their rivals after winning a first derby in 13 attempts in December's Scottish Cup fourth-round clash, little more than six months after losing the Hampden final 5-1 to the same opponents.
Hearts are six points behind Hibs, after playing one game less, and could cut the deficit to three points with victory.
With the winter break beginning after the Tynecastle tussle, Fenlon is eager to keep the momentum from the Celtic win going.
"It would be great to go there and get something out of the game," Fenlon added.
"On the back of beating Celtic, you want to be able to go and back that up.
"If we could go there and win it would be a fantastic result, but we're under no illusions, we know it's going to be difficult.
"We're looking forward to it. We feel we're a match for anybody in the league at the moment."
Fenlon has been reluctant to comment on Hearts' strife this season.
He added: "I don't get too much caught up in what goes on across the city. I can't control it.
"I'm more interested in what we can do here. As a club we've progressed.
"We've changed a lot of things round and we're moving the club forward. I think that's all we can worry about and focus on."
Fenlon does not anticipate Hibs being full of activity during the winter transfer window as he still hopes to extend stays for striker Leigh Griffiths, defender Ryan McGivern and midfielder Jorge Claros, whose loan deals are up this month.
Fenlon added: "It will depend where we get with the three players. If we keep the three of them, that will probably be it.
"We don't have loads of money, unless one or two players leave and we'll have to replace them.
"I'm more than happy with the squad we have. We've got a decent squad.
"Like most managers, you'd love to add one or two more, but you have to be realistic as well, know where we are as a club and work within that."
McGivern missed the win against Celtic with a hamstring problem, Lewis Stevenson taking his place at left-back.
Stevenson impressed, giving Fenlon food for thought after McGivern came through training today.
Fenlon added: "We didn't risk him against Celtic. Lewis came in and was fantastic.
"It's given me a headache, but it's a good one to have. He was excellent at the weekend."
The Scotland international was left out of West Brom's 18-man squad for their New Year's Day defeat by Fulham despite being fit.
It is understood he and the club have come to a mutual agreement that he can leave if a suitable deal is agreed during the transfer window.
Dorrans signed a long-term contract in July 2010 which tied him to the club until the summer of 2015, shortly after West Ham had several bids for the player rejected.
Dorrans has 18 months left on his contract but West Brom retain the option of another year so are likely to seek a sizeable fee for the 25-year-old, having rejected a ?5million offer from the Hammers.
Dorrans joined the Baggies from Livingston in 2008 and has made more than 130 appearances for the club, 12 of them since Steve Clarke took over as manager in the summer.
West Brom were unavailable for comment.
