Match ends, Manchester United Women 2, West Ham United Women 0.
Teenager Lauren James scored as Manchester United claimed victory over struggling West Ham on a historic day that saw Old Trafford host a Women's Super League match for the first time.
James, 19, rose to flick home Maria Thorisdottir's header from a corner to make it 1-0 just after the break.
USA forward Christen Press thumped in a second after she was slipped through by Jackie Groenen six minutes later.
United, who usually play at Leigh Sports Village, sit third in the table.
James, one of England's most promising youngsters, was excellent in the first half and was rewarded for her fine performance when she became the first woman to score at Old Trafford just five minutes after the restart.
She has now scored the first goal for Manchester United women in the Championship, the WSL, the FA Cup and now at Old Trafford.
James showed skill, intelligence and pace throughout, coming close again in the second half when her curling strike flew inches past the right post.
Before her opener, the hosts were struggling to break down West Ham, who remain bottom of the table and without a win in seven WSL matches.
Press had opportunities to score and twice fizzed balls across the six-yard area which evaded James and midfielder Ella Toone.
Sloppiness in possession almost proved costly for the hosts too as West Ham's Martha Thomas, Kenza Dali and Dagny Brynjarsdottir all had chances to get in behind the home defence in the first half after being gifted the ball.
The Hammers were made to pay for not taking their chances though as James and Press provided the clinical edge Manchester United had craved, before Laura Vetterlein's second yellow card made life even harder for the visitors in the final stages.
The result leaves Casey Stoney's side six points above Arsenal, who take on north London rivals Spurs at the Tottenham Hotspur Stadium later on Saturday (15:30 GMT).
West Ham are one point below Bristol City, who face fellow relegation rivals Birmingham City on Sunday (16:00 GMT).
'You wouldn't even dream it!' - what they said
Manchester United manager Casey Stoney: "We weren't good in the first half - that was probably the worst I've seen us in a long, long time, so I think there was definitely a case of the occasion. That's done now. They know what it's like.
"Players know when they are not good enough. I said [at half-time] if you want to qualify for Champions League football, you have to play at a Champions League standard and we weren't.
"When we started playing collectively in the second half we were better."
Manchester United midfielder Ella Toone: "As a Manchester United fan it was a dream come true to play on such an amazing pitch so it was a special occasion and I'm glad we went out there and got the three points."
West Ham boss Olli Harder on playing at Old Trafford: "The players all thoroughly enjoyed the opportunity to be here. It was a decent promotion for women's football.
"For somebody who grew up at the bottom of the world and only seeing Old Trafford on TV, to say it was a dream to come here and coach is not even true because you wouldn't even dream it! It's not real when you live in New Zealand.
"It was a fantastic occasion for myself personally but more importantly, for the girls to come and play at arguably one of the most historic stadiums in the world."
Man Utd Women
- 4TurnerBooked at 61mins
- 17BatlleBooked at 67minsSubstituted forHarrisat 74'minutes
- 10ZelemSubstituted forLaddat 65'minutesBooked at 90mins
- 37StaniforthSubstituted forHansonat 66'minutes
- 16JamesSubstituted forRossat 84'minutes
- 24PressSubstituted forSigsworthat 84'minutesBooked at 90mins
West Ham Women
- 26VetterleinBooked at 77mins
- 2Redisch KvammeSubstituted forBarkerat 89'minutes
- 32BrynjarsdóttirSubstituted forCissokoat 84'minutes
- 21DaliSubstituted forMustafaat 88'minutes
- 25van Egmond
- 9ThomasSubstituted forPachecoat 78'minutes
- Lisa Benn
- Shots on Target
Second Half ends, Manchester United Women 2, West Ham United Women 0.
Attempt missed. Mayumi Pacheco (West Ham United Women) header from the centre of the box is close, but misses to the left. Assisted by Kate Longhurst following a set piece situation.
Hayley Ladd (Manchester United Women) is shown the yellow card for a bad foul.
Foul by Hayley Ladd (Manchester United Women).
Gilly Flaherty (West Ham United Women) wins a free kick in the attacking half.
Foul by Maria Thorisdottir (Manchester United Women).
Katerina Svitková (West Ham United Women) wins a free kick in the defensive half.
Attempt missed. Kirsty Hanson (Manchester United Women) left footed shot from the centre of the box misses to the left. Assisted by Ella Toone.
Offside, Manchester United Women. Jane Ross tries a through ball, but Jackie Groenen is caught offside.
Attempt missed. Ella Toone (Manchester United Women) right footed shot from the right side of the box is high and wide to the left. Assisted by Jessica Sigsworth.
Jessica Sigsworth (Manchester United Women) is shown the yellow card for a bad foul.
Foul by Jessica Sigsworth (Manchester United Women).
Mayumi Pacheco (West Ham United Women) wins a free kick in the defensive half.
Attempt missed. Maisy Barker (West Ham United Women) right footed shot from outside the box is too high. Assisted by Gilly Flaherty following a corner.
Corner, West Ham United Women. Conceded by Maria Thorisdottir.
Foul by Amy Turner (Manchester United Women).
Nor Mustafa (West Ham United Women) wins a free kick in the attacking half.
Attempt missed. Millie Turner (Manchester United Women) header from the centre of the box misses to the right. Assisted by Ella Toone with a cross following a corner.
Substitution, West Ham United Women. Maisy Barker replaces Cecilie Redisch Kvamme.
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