Romelu Lukaku scored for the second straight Premier League game to set Manchester United on its way to a 2-1 win at West Bromwich Albion on Sunday.
The striker, who spent the 2012-13 season on loan at West Brom, didn't celebrate after heading in Marcus Rashford's inswinging cross in the 27th minute. Lukaku reacted the same way after scoring a near-identical header in United's 1-0 win over Bournemouth on Wednesday, suggesting there is an underlying reason for his unhappiness.
The Belgium international has been criticized in recent weeks, having scored just once in the league in 2 1/2 months before the goal against Bournemouth. Lukaku had started the season with seven goals in his first seven league games.
Jesse Lingard added the second in the 36th for second-place United, which was forced to hold on for a victory that trimmed the gap to Manchester City to 11 points. Substitute Gareth Barry cut the deficit for West Brom at a corner in the 79th minute.
It was an efficient, unspectacular display from United, which lost captain Antonio Valencia to an apparent hamstring injury midway through the second half and then lost its way as West Brom finished strongly at The Hawthorns.
There was a worrying moment for United in the last few minutes when Chris Brunt's corner to the far post was nearly bundled into his own net by Nemanja Matic.
"I think less ambition after the break," United manager Jose Mourinho said, in explaining his team's second-half dip. "The intensity in the first half maybe we didn't have in the second half. West Brom are really powerful in the air."
United reclaimed outright possession of second place after Chelsea moved level on points on Saturday.
Barry's close-range strike is West Brom's only goal in four matches under new manager Alan Pardew that have ended in two draws and two losses, keeping the team in the relegation zone heading into the busy festive period.
This result extended West Brom's club-record winless run in all competitions to 17 games, the longest in its 139-year history.
Pardew felt he got his team selection wrong, saying he should have freshened it up after the midweek 0-0 draw at Liverpool.
"I should have maybe made two or three change," Pardew said. "We just had a lack of energy and I have to take some blame for that."
Pardew's side had managed to keep Liverpool's prolific strikeforce at bay at Anfield but conceded the opener against United in the simplest of ways, a cross by Rashford from the left wing met by a glancing header from Lukaku into the top corner for his 15th goal in all competitions this season.
Lukaku showed more delight after Lingard scored the second goal in the 36th, the winger sending in a low shot from 25 meters that deflected off the outstretched foot of West Brom defender Ahmed Hegazi and past goalkeeper Ben Foster.
"I think we deserved it, I think we were the best team," Mourinho said. "I think we controlled the game for a long time."
(With AP Inputs)