Manchester United moved closer to a record-breaking 19th league title on Saturday by beating Fulham, while relegation-threatened West Ham, Wigan and Wolverhampton Wanderers all lost.
"It was an important win, that is the name of the game, but we did not play that well and we were a bit wasteful in possession," United manager Alex Ferguson said.
Chelsea moved ahead of Manchester City into third after Florent Malouda clinched a 1-0 win over bottom-place Wigan.
Wolves and West Ham are a point ahead of Wigan and both lost 3-0. Wolves crashed at home to Everton and West Ham was beaten at Bolton.
Tottenham recovered from Tuesday's 4-0 loss at Real Madrid, with Peter Crouch's double clinching a 3-2 victory over Stoke.
Galloping toward the championship crown will bring some consolation to Ferguson on the day his horse, What A Friend, failed to win the Grand National.
Berbatov, who started up front as Wayne Rooney began serving a two-match ban for swearing, netted a league-leading 21st goal of the season after 12 minutes.
The Bulgaria striker was given the benefit of the doubt with a very tight offside decision, slotting a shot beyond goalkeeper Mark Schwarzer after Nani flicked the ball into his path.
Valencia doubled the lead in the 32nd minute when he headed home from close range after Aaron Hughes had tried to clear Nani's goalbound effort.
Malouda ensured Chelsea did not lose further ground on United, with Carlo Ancelotti's side 11 points adrift with a game in hand.
The French midfielder drove home a shot through a crowd of players for his first goal in more than three months, while Fernando Torres' scoring drought continued after starting on the bench for the second straight league game. He came on for Nicolas Anelka with 31 minutes remaining.
Tottenham moved to within three points of Manchester City in fourth, with Crouch putting his midweek red card in the Champions League quarterfinals behind him.
After 11 minutes, the England striker headed in Roman Pavlyuchenko's cross. Pavlyuchenko also set up the second for Luka Modric, but Matthew Etherington pulled one back after a superb run.
Crouch restored the two-goal lead with another header, and though Kenwyne Jones reduced the deficit before halftime, Stoke couldn't find an equalizer in the second half.
"We've had a setback at Real Madrid," Tottenham manager Harry Redknapp said. "But we've got to come back and go on a run in the league and try to get back in that top four."
While Stoke lost, its FA Cup semifinal opponent next Sunday - Bolton - routed West Ham thanks to Daniel Sturridge's double and Lee Chung-yong's header.
First-half goals from Jermaine Beckford, skipper Phil Neville and Diniyar Bilyaletdinov secured Everton's win at Wolves.
Liam Ridgewell's mistake helped Blackburn take a 1-1 draw in a home match against Birmingham as both sides moved three points clear of the relegation zone.
David Hoilett robbed the Birmingham defender of the ball before converting in first-half stoppage time to cancel out Lee Bowyer's headed opener.
West Brom continued their resurgence under coach Roy Hodgson, who took charge in February, by twice coming from behind to win 3-2 at Sunderland and move into the top half of the table.
Arsenal travels to Blackpool on Sunday when Aston Villa hosts Newcastle. Manchester City makes the short trip to Liverpool on Monday.
