Jose Mourinho highlighted a lack of attacking ambition as the reason for West Brom's fightback as Manchester United recorded their third straight Premier League away win with a 2-1 victory at The Hawthorns.
First-half goals from Romelu Lukaku and Jesse Lingard put second-placed United on track for their sixth win in seven Premier League matches.
But United eased off after the interval, with substitute Gareth Barry scrambling in West Brom's first goal under Alan Pardew to set up a nervy finale in Sunday's match.
Mourinho insisted his side still did enough to win the game while acknowledging West Brom battled back well in the second half.
"I think [United had] less ambition, the intensity in the first half maybe we didn't have in the second half," Mourinho told Sky Sports.
"Probably we lost a bit of ambition. But they are really powerful in the air - they have giants and aggressive people in the air.
"But after their goal we controlled the game again. We brought the ball into the opposition half and they didn't have much more after that.
"I think we deserved the win. We were the best team. I knew and the players knew that West Brom are very dangerous on set-pieces.
"[Former West Brom head coach] Tony [Pulis] is an expert on that - very strong and physical on set-pieces and we knew that it could be a problem.
"We controlled the game for a long, long time, then Alan reacts with a few changes to try to give the team more width and quality with a second striker in the middle.
"We had a few chances to kill the game but I knew they would react. So when they scored it's normal, but we deserved the victory overall."
United were dealt a blow when captain Antonio Valencia limped off, with Mourinho blaming fatigue for the full-back needing to be replaced.
"That's football in England, especially in December," Mourinho added. "Players are not machines and sometimes it happens.
"He knew he was not going to play the next game [Wednesday's EFL Cup quarter-final at Bristol City] and he was asked for a last effort before the break but he couldn't resist.
"We have other players, [Daley] Blind and [Matteo] Darmian were not on the bench, and we have other people to cope with the difficulty."
|Guardiola: Quadruple-chasing City will only be judged on trophies|
|Chelsea lacked finances to compete with City & United for Sanchez - Conte|
|Batshuayi out of chances to convince Conte|
|Sevilla 3 Atletico Madrid 1 (5-2 agg): Griezmann stunner not enough for semi spot|
|Bristol City 2 Manchester City 3 (3-5 agg): Guardiola through to first English final|
|O´Neill signs Ireland extension|
|New signing Jach sees Palace as platform for World Cup spot|
|Phil Neville appointed England Women´s manager|
|Kenedy leaves Chelsea for Newcastle loan|
|PSG rule out ´traumatic´ injury for Mbappe|
|PSG boost midfield options with surprise Diarra signing|
|Dyche commits to Burnley to 2022|
|Zidane tells Real Madrid fans to stop jeering Benzema|
|Lucas Moura free to leave PSG, confirms Emery|
|Kenedy set for Newcastle as Conte waits for window to close|
|Neymar and Mbappe in doubt for PSG´s clash with Guingamp|
|Mascherano to leave Barcelona as Hebei move looms|
|Conte rules Morata and Fabregas out of Arsenal clash|
|Clarets snap up Lennon from Everton|
|Dzeko set to face Sampdoria despite Chelsea reports|
|Zidane rejects suggestions he won ´battle´ over Kepa|
|Ramos trains for Real Madrid as wounded Ronaldo works indoors|
|Wijnaldum admits Liverpool ´gave a half away´ against Swansea|
|Wenger: Arsenal are about values, not millions|
|Aubameyang to Arsenal not close, says Wenger|
|Hernandez open to West Ham exit|
|Superstar Sanchez will lift Manchester United squad, says Giggs|
|De Bruyne 2023: The sensational displays that won Manchester City´s talisman a new deal|
|How new recruit Sanchez compares to Manchester United´s forwards|
|Lucas ´not happy´ at PSG|
|Stones: Quadruple chase will take its toll on City|
|Klopp sorry for fan confrontation|
|Buffon guaranteed to start on Juventus return, assures Allegri|
|Liverpool´s win over City feels like six months ago for Klopp|
|Swansea had to make ´Formula One´ Liverpool uncomfortable - Carvalhal|
|Swansea City 1 Liverpool 0: Mawson ends Reds´ unbeaten run|
|Juventus 1 Genoa 0: Douglas Costa goal closes the gap to leaders Napoli|
|Lingard knew Sanchez ´wanted to come Milly Rock with the mandem´|
|Wenger ecstatic with ´committed and focused´ Mkhitaryan after Sanchez swap|
|Sanchez on United move: I needed to feel loved|
|Sanchez takes aim at his critics as he says his Arsenal goodbyes|
|How will Alexis Sanchez compare to Manchester United´s post-Ferguson big deals?|
|Gunning for a move - Sanchez the latest big name to quit underachieving Arsenal|
|Stoger wants speedy Aubameyang resolution as Arsenal circle|
|WATCH: See how Manchester United welcomed Sanchez|
|WATCH: Treatment-room footage of Ronaldo head wound released|
|Always my intention to stay - De Bruyne thrilled by new City deal|
|Inter snap up Rafinha on loan from Barcelona|
|Sanchez on Man Utd move: I am joining the biggest club in the world|
|The big debate: Who wins from the Sanchez-Mkhitaryan deal?|
|Mkhitaryan wants to ´create history´ after ´dream´ Arsenal move|
|Do Arsenal or Man Utd get the better deal? Sanchez v Mkhitaryan in Opta numbers|
|Manchester City reward De Bruyne with new five-year deal|
|Arsenal and Man Utd agree Sanchez-Mkhitaryan swap|
|Spurs striker Kane voted England Men´s Player of the Year|
|Aubameyang behaviour ´unreal´, says Frankfurt boss Kovac|
|Van Persie: Feyenoord return a choice for continuity|
|Hamburg hire Hollerbach to replace Gisdol|
|New Bordeaux coach Poyet offered Malcom assurances|
|Rakip excited to link up with ´legend´ Hodgson at Crystal Palace|
|O´Neill rejects Scotland to stay on as Northern Ireland boss|
|Simeone: Atleti must seize early control against Sevilla|
|Vermaelen sidelined for two weeks|
|Silva ranks Man City star De Bruyne with Ronaldo among world´s best|
|Former England captain Armfield dies aged 82|
|Robinho set to join Sivasspor|
|Van Persie´s Feyenoord return ´beautiful and special´|
|Kepa pens new Athletic Bilbao deal amid Madrid speculation|
|PSG star Mbappe holds no grudge against Lopes after Lyon collision|
|Messi makes football better, says beaten Real Betis goalkeeper|
|Goretzka accepts vitriol from Schalke fans after Bayern move|
|What am I getting for my birthday? Arsenal-bound Mkhitaryan celebrates with Pogba|
|Ince: Sanchez snubbed City because United are miles bigger|
|Bale: Madrid will get back to their best|
|Valverde: Messi is the best player there is and there ever will be|
|Emery: Lyon loss unfair on PSG|
|Spalletti defends struggling Inter amid six-game winless run|
|Fekir: Lyon still targeting Champions League despite PSG win|
|Wenger suggests Sanchez is joining Manchester United for money|
|Hazard: Chelsea don´t need to buy a striker|