Sergio Aguero and Ilkay Gundogan each scored twice as Manchester City crushed West Bromwich Albion 4-0 on Saturday to reclaim first place in the Premier League from Arsenal.

Arsenal won 4-1 at Sunderland, with substitute Olivier Giroud and Alexis Sanchez both scoring twice, but City's win kept Pep Guardiola's side top on goal difference as they ended a six-game winless run.

"When we lose there are always doubts," said Guardiola. "It's the first time I have not won in six games. Always you have doubts, (but) not over the principles."

Jose Mourinho was sent to the stands at Old Trafford and Ander Herrera dismissed as Manchester United drew 0-0 with Burnley despite having 37 shots at goal, while champions Leicester City drew 1-1 at Tottenham Hotspur.

Guardiola, whose side host former club Barcelona in the Champions League on Tuesday, made eight changes to his starting XI from Wednesday's 1-0 League Cup defeat at Manchester United.

Aguero was among the players to return to City's starting line-up at The Hawthorns and his first-half brace effectively settled the game.

He broke the deadlock in the 19th minute, slamming a shot between Ben Foster's legs from Gundogan's pass, and doubled his tally nine minutes later with a stunning shot from the edge of the box.

The goals ended Aguero's six-game scoring drought and lifted his City tally to 149 -- one more than club great Francis Lee.

Aguero teed up Gundogan for City's third in the 79th minute and the former Borussia Dortmund midfielder sealed victory in the last minute of normal time.

"We need Sergio," said Guardiola, who dropped the Argentina striker for City's 4-0 defeat at Barcelona. "He is one of the best."

Arsenal had earlier strolled to victory at bottom club Sunderland, who are now seven points from safety and without a win after 10 league games.

Sanchez put Arsenal in front in the 19th minute with a header from an Alex Oxlade-Chamberlain cross.

Jermain Defoe equalised from the spot in the 65th minute after Petr Cech was booked for impeding Duncan Watmore.

But Giroud equalised six minutes later, volleying in a Kieran Gibbs cross with his first touch after coming on.

The France striker struck again five minutes later, a looping header from Mesut Ozil's corner, and Sanchez completed the scoring two minutes after that with a neat close-range finish.