A controversial first-half penalty by Ruud van Nistelrooy secured the points for the injury-hit champions, who are bidding for a record fourth successive title.
The Dutchman tumbled in the area under pressure from two Ipswich defenders before keeping his cool to slot his 23rd league goal of the season.
Victory lifted Alex Ferguson’s side above Liverpool into second place, two points behind leaders Arsenal who visit Bolton Monday knowing they have a game in hand on their title rivals.
Liverpool’s push for their first league title since 1990 suffered a heavy blow earlier in the day when they slumped to a 1-0 defeat at Tottenham.
Gerard Houllier’s side trail Arsenal by four points with two games to play.
Ipswich must now win their final game — away to Liverpool — and hope that Sunderland lose at home to relegated Derby in order to secure their survival in the top flight.
Earlier, a 41st-minute goal by Gustavo Poyet gave Tottenham Hotspur a 1-0 win over Liverpool in a noon kick-off at White Hart Lane.
It was Liverpool’s first defeat in 15 league games and their fourth in their last four matches at Spurs.
At the other end of the table Kevin Lisbie struck an 82nd-minute equaliser as Charlton Athletic held Sunderland 2-2 at The Valley.
Peter Reid’s slumping side stayed fourth-from-bottom, one place and three points above the drop zone with one game left. They need only a point against second-bottom Derby in two weeks’ time to survive.
An explosive start at The Valley produced two goals in the first two minutes. Jason Euell put Charlton ahead after 64 seconds but Kevin Kilbane immediately equalised for Sunderland.
Kevin Phillips gave the visitors the lead after 11 minutes, his first goal in 11 games, and Peter Reid’s side hung on in a fiercely-fought second half until eight minutes from the end when Lisbie’s close range overhead kick made it 2-2.
In-form Newcastle still have an outside chance of finishing in the top three to qualify directly for the first group stage of the Champions League.
Jermain Defoe gave West Ham the lead at St James’ Park but strikes by Alan Shearer, Lomano Lua Lua and Laurent Robert sealed victory for Bobby Robson’s side, who have 71 points in fourth place.
Eighteen-year-old Carlton Cole marked his full debut for FA Cup finalists Chelsea with a 38th-minute strike at Middlesbrough and a second by Dutchman Boudewijn Zenden five minutes later secured the points for the Londoners, who stayed fifth.
Sixth-placed Leeds United also won, 1-0 at relegated Derby County, thanks to Lee Bowyer’s deft first-half finish.
England coach Sven-Goran Eriksson will have been concerned, however, at the sight of Robbie Fowler hobbling off with a bruised hip.
Two goals by England striker Darius Vassell helped Aston Villa to a 2-1 victory over Southampton at Villa Park, while Fulham’s last match at their old Craven Cottage ground before it is redeveloped ended finished 0-0 against doomed bottom club Leicester.
Saturday’s results:
Aston Villa 2 Southampton 1
Charlton Athletic 2 Sunderland 2
Derby County 0 Leeds United 1
Fulham 0 Leicester City 0
Ipswich Town 0 Manchester United 1
Middlesbrough 0 Chelsea 2
Newcastle United 3 West Ham United 1
Tottenham Hotspur 1 Liverpool 0
—Reuters