Brendan Rodgers had no complaints with the result after Liverpool's recent resurgence was brought to a halt by a 3-1 defeat at Southampton.
Liverpool had won three Premier League games in a row to raise hopes of European qualification, but produced a ragged performance at St Mary's, particularly in the first half.
Rodgers was disappointed with the goals his side conceded on the South Coast and admitted Liverpool did not get going until they were 2-0 down.
"I thought Southampton deserved to win," Rodgers told Sky Sports. "We were nowhere near what we've been in the last number of weeks.
"It's very difficult at this level whenever you make the start we made today of being two goals behind. We only started to play when it went to 2-0.
"The three goals conceded were disappointing goals today, but in between the second goal and the third goal we were very good.
"We got to 2-1 just before half-time and had more fluency and flow in our game. We created chances, but then conceded a poor third goal that was far too easy and from that perspective it was bitterly disappointing."
The international break means Liverpool do not play for a fortnight and Rodgers wants a positive response in the next game at Aston Villa.
He added: "I said before the game that this game was arguably going to be one of the toughest games for us this season and overall I can't complain.
"We weren't at our best and we're not the sort of team yet when, if we're not at our best, we can see through results.
"We have to lick our wounds for a couple of weeks before the next game, and we have to make sure it was a one-off and we get back to how we were playing, at a real high level and with confidence."
The first, in the 62nd minute, was a sensational right-footed strike from 20 yards after Harrison had turned his marker on the right and cut in past another defender.
Rochdale substitute Michael Rose equalised with a superb strike from 25 yards after 75 minutes, but Harrison pounced to net from close range when the visitors failed to deal with Eliot Richards' 84th-minute cross.
Rochdale hit a post through George Donnelly's 57th-minute shot and could consider themselves unlucky losers.
They created the best chances of a scrappy first half, with Donnelly's 20th-minute glancing header from a Robert Grant cross flying inches wide.
Donnelly had earlier shot over when unmarked 15 yards out and he went close again on the half hour when just failing to get a meaningful touch to a Rose cross.
Rovers goalkeeper Steve Mildenhall had to produce a fine 45th-minute save to keep out a curling Grant shot.
Kris Commons fired the home side into the lead inside 15 seconds - but instead of a Hoops romp, Scott Vernon levelled with a minute of the first half remaining and Josh Magennis grabbed a double to set the Dons on the way to what would have been an unlikely victory.
However, Celtic showed the spirit of champions and Charlie Mulgrew reduced the deficit before Gary Hooper equalised with three minutes remaining, leaving the stage set for sub Samaras, who had replaced Beram Kayal, to hook in the winner with seconds left.
Billy McKay's controversial penalty secured Inverness a 2-1 home win against Highland rivals Ross County, lifting them above the Staggies into third place in the table.
The Northern Ireland striker's 24th goal of the campaign ended County's 11-game unbeaten run and has all-but ensured Inverness will have their first ever top-six SPL finish.
McKay netted the winner in the 59th minute after referee Iain Brines pointed to the spot when Charlie Taylor went down, but there were strong suggestions the full-back was making a meal of it.
It came after Andrew Shinnie's close-range opener in five minutes for Caley Thistle was cancelled out by a magnificent 30-yard strike from County's Paul Lawson.
The defeat leaves County fourth, two points behind Inverness.
