Juan Mata came off the bench to secure Manchester United's first win in four Barclays Premier League matches with a 1-0 victory over Crystal Palace.
As in last weekend's loss to rivals Manchester City, Spaniard Mata began among the substitutes, but he staked his claim to be a bigger role in weeks to come by firing a deflected winner in the 67th minute - shortly after joining the action.
Palace goalkeeper Julian Speroni might have done better than palming Mata's strike into his own net and Neil Warnock's men were also left to reflect on a glorious chance passed up by former United youngster Fraizer Campbell before half-time.
Marouane Fellaini had a header cleared off the line before Mata’s strike eased the tension at Old Trafford and condemned Palace to a fifth consecutive match without victory - only goal difference keeping them out of the bottom three.
A shoulder injury for Marcos Rojo and Chris Smalling's red card during the Manchester derby compounded Van Gaal's selection problems in defence and the United manager paired youngster Paddy McNair and Daley Blind at centre-back, with Michael Carrick taking the Netherlands international's customary midfield spot.
James McArthur replaced suspended Palace captain Mile Jedinak, while Jason Puncheon came in as winger Wilfried Zaha was ineligible against his parent club.
McArthur's midfield partner, Joe Ledley, was careless in possession in the second minute, allowing Adnan Januzaj - making a fourth consecutive United start - to cut inside and fire a left-footed effort narrowly over the crossbar.
Palace forward Marouane Chamakh failed to make decisive contact with a 14th minute free-kick after Wayne Rooney had needlessly fouled Puncheon, but the visitors rarely ventured out of their own half with any intent during the opening stages.
Equally, Palace's defence comfortably repelled much of what the United attack threw at them, leaving left-back Luke Shaw to charge towards the massed ranks and drill narrowly wide in the 27th minute.
United's makeshift centre-back pairing presented Campbell with the first-half's clearest opening against his former club, but he failed to punish their confusion by lifting a shot over on the end of Joel Ward's long ball.
Rooney, largely subdued in his midfield role, side-footed wide from 20 yards in the 53rd minute after McNair had emulated Shaw by running at a deep-lying Palace defence.
United and Palace have both shown frailties defending set-pieces this season and the visitors were almost undone when Fellaini's header from a Rooney corner was blocked on the line by McArthur.
The former Everton man was the target once more when he grappled with Damien Delaney to head over in the 62nd minute, immediately before United's match-winner entered the fray.
Yannick Bolasie scuffed a volley from Puncheon's cross as Palace enjoyed a promising attacking but then Angel Di Maria passed to Mata and the playmaker's speculative shot evaded Speroni.
Mata clattered an 83rd minute shot against the post before United closed out a triumph that lifts them to sixth in the table.
Manchester United manager Louis van Gaal: "It was a fantastic goal but it was important also. It is always difficult to attack against a defending team, who comes here to defend and not attack. You have two rows of four and we created a lot of possibilities. I am pleased because we have three points and there is an international break so it was important we closed with a victory.
"Juan Mata has played a lot of matches. I have given him the chance, I give other players the chance and at the end we shall see who plays more than the other. It is always like that in football. They [McNair and Blind in defence] didn't have to defend too much because we always had the ball. They only had to defend the long balls but that is difficult because Chamakh and Campbell are strong headers of the ball. Paddy McNair is not injured. It was cramp. It is [recent injury problems] crazy but it is what I have to deal with."
Crystal Palace manager Neil Warnock: "We are having that kind of spell at the minute, nothing going right for us. If Fraizer Campbell had scored that chance he had it would have put a lot of pressure on them, but it was not to be. I thought the referee did well today, I am just disappointed to concede the goal. I think Julian Speroni will have been disappointed.
"It is hard at times for a lot of clubs at this level but you just have to keep going. I can't criticise the lads today. The passing was poor at times, though, we made some bad decisions with the ball. You have to work hard to make your own luck. Liverpool next, after last year that should be a cracking match and I am looking forward to it."
Manchester United have failed to score in the first half in each of their last four Barclays Premier League Barclays Premier League matches. United’s last four BPL matches have produced a total of just one first-half goal (for West Brom – 20 October).
Angel Di Maria has assisted three of the Red Devil’s last five Barclays Premier League goals. Indeed, he has been involved in four of United’s last six Barclays Premier League goals (one goal, three assists)
Crystal Palace have shipped a league-high 13 second-half Barclays Premier League goals.
Palace have failed to score in nine of the 11 Barclays Premier League meetings with Manchester United.
United are unbeaten in five league matches at Old Trafford, winning four and drawing one, their longest unbeaten home run since March 2013 (under Sir Alex Ferguson).
Palace have registered a victory in just one of their last seven Barclays Premier League matches on the road, losing three and drawing three.
|02 Dec 2014||v Stoke (H)|
|14 Dec 2014||v Liverpool (H)|
|29 Nov 2014||v Hull (H)|
|08 Dec 2014||v Southampton (A)|
|20 Dec 2014||v Aston Villa (A)|
|22 Nov 2014||v Arsenal (A)|