Jose Mourinho praised the impact of two-goal Jesse Lingard after Manchester United's 3-1 Premier League win at Arsenal.
The England midfielder struck United's second after 11 minutes and a second-half third as Arsenal were pushing for an equaliser.
"He played well," United boss Mourinho said.
"He did what the team needed him to do, defensively and also in terms of going into finishing areas.
"We worked pre-season well and hard about playing sometimes with three at the back, sometimes four.
"When we play with two strikers we need people from the midfield that can arrive in finishing situations and that's what Jesse did for us."
Greater responsibility may fall on Lingard in the coming weeks when Paul Pogba will be suspended for second-placed United.
A straight red card shown to Pogba for a studs-up challenge on Hector Bellerin will see the France midfielder miss next Sunday's Manchester derby, plus the Premier League fixtures with Bournemouth and West Brom.
Pogba is likely to feature on Tuesday night when United will seek to secure their place in the Champions League knockout stages against CSKA Moscow.
Arsenal are in Europa League action on Thursday against Belarus' BATE Borisov before playing at Southampton next Sunday.
The defeat ended a 12-game winning run at home in the league and was the Gunners' fifth in 15 league games this season.
The loss was largely self-inflicted as mistakes from Laurent Koscielny and Shkodran Mustafi proved costly in the opening 11 minutes before David De Gea made a series of fine saves to frustrate the hosts.
Goalkeeper Petr Cech said on arsenal.com: "The game was decided at the start with our two mistakes and they scored.
"We need to make sure that when we create chances in a big game we score and don't make mistakes.
"There are not many times you play United and you dominate the whole game, having so many chances, so this is positive, but we are disappointed.
"We played against Huddersfield and we were on the other side of it (winning 5-0 last Wednesday).
"We had a spell where we had four shots and everything went in, this time it was the opposite."