Manchester United provisionally moved within one point of the Premier League summit following a 2-0 win over West Bromwich Albion on Saturday.
Both sides labored in a first half lacking any real purpose and it wasn't until the second that United went ahead.
The hosts took the lead within minutes of the restart when Jesse Lingard curled in from the edge of the area, his first senior goal for United.
Substitute Saido Berahino headed Albion's best chance over the bar in the 76th. The unmarked substitute failed to direct Stephane Sessegnon's cross at goal shortly after his introduction.
Martial won United a penalty in second-half stoppage time after being felled by Gareth McAuley. The West Brom defender was shown a straight red card and Juan Mata converted the spot kick.
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