A superb Diego Costa strike stretched Chelsea’s winning run to nine matches, equalling their streak from 2007, after they overcame West Brom 1-0 yesterday in the Premier League.

Costa’s 12th goal of the season sees the Blues maintain their three-point advantage over Arsenal who briefly went top on goal difference after beating Stoke 3-1 on Saturday.

The Gunners’ north London rivals Spurs lost ground after going down to a 1-0 defeat at Manchester United. Spurs remain in fifth on 27 points, 10 adrift of Chelsea.

United, for whom Henrikh Mkhitaryan opened his account in the Premier League before going off on a stretcher in the second-half with what appeared a left ankle injury, are 13 points shy of the leaders but only six off the Champions League spots.

United manager Jose Mourinho, who said he didn’t think the injury to Mkhitaryan was serious and that the player risked missing just two weeks, hailed the three points haul as “magic”.

West Brom made it difficult for Chelsea at Stamford Bridge until Costa seized on the ball 14 minutes from time, brushed off the attention of Gareth McAuley and rifled the ball past Ben Foster into the top far corner.

Chelsea manager Antonio Conte feted his players for winning nine in a row — scoring 23 and conceding just two goals — in a “very tough league”.

“I’m very happy. We faced a tough, physical team. They’re difficult to break down and we showed great patience to find the right solution,” said the 47-year-old Italian.

“It wasn’t easy but my players showed great character and motivation to win.

“We are working very well. When you don’t find the goal, it becomes more difficult but we were very good to find in the right moment to do it.”

The United and Spurs match was of a far better quality with the hosts going close through Paul Pogba, who hit the post and also forced Spurs’ French goalkeeper Hugo Lloris into a superb save in the second-half.

The visitors could have gone home with a share of the points but for a woeful misdirected header from unmarked Kenyan midfield enforcer Victor Wanyama.

“Our heart was in our hands but the players gave us everything. These three points are magic because it’s against a very good team so it means more for us,” Mourinho told Sky Sports.

In a match involving two struggling teams, Southampton ended a bad week with a much-needed win, beating Middlesbrough 1-0.

Record signing Sofiane Boufal secured the three points with a delightful effort from the edge of the area.

Victory — only Southampton’s second in seven matches — moves Saints eight points clear of the relegation places while ‘Boro remain mired in the battle for survival, just three points better off than third from bottom West Ham.

RESULTS

Chelsea 1-0 West Brom

Man Utd 1-0 Tottenham

S’thampton 1-0 M’brough

Liverpool 2-2 West Ham