Marcos Alonso's long-range free-kick gave Chelsea a 1-0 win over Southampton at Stamford Bridge on Saturday.
The Spaniard struck on the stroke of half-time, curling a stunning effort around the wall and beating Fraser Forster, who will feel he should have done better.
Chelsea dominated the game for long periods but were unable to extend their lead, with Pedro hitting the post in the first half and Forster making a string of saves.
Chelsea's wastefulness was almost punished as Southampton substitute Charlie Austin went close to equalising twice in the second half, but Antonio Conte's side held out to move level on points with second-placed Manchester United.
Chelsea's first real chance in a one-sided first half fell to Willian, but his low effort from 10 yards out rolled wide of the post after a neat one-two with Alonso in the Southampton box.
The visitors were forced to replace the injured Cedric Soares with Mario Lemina following a heavy tackle by Gary Cahill in the early stages, and they struggled to get out of their half after that.
Forster made two saves from Alonso either side of a stop from N'Golo Kante, but Southampton needed the woodwork to rescue them when Pedro cut inside from the left flank two minutes before half-time.
Just as it seemed Southampton might hold out until the break, however, Alonso took advantage of Maya Yoshida's foul on Eden Hazard 30 yards from goal to put the hosts in front.
Mauricio Pellegrino turned to Austin on the hour mark and the Englishman, who had scored four times in his previous five appearances, forced Courtois into a diving save with his first touch.
It was a warning sign for Chelsea, and Austin threatened again in the 76th minute, when Courtois denied him in a one-on-one situation again.
Forster made second-half saves from Alonso, substitute Alvaro Morata and Cesc Fabregas as Chelsea pushed for a second goal, but in the end they were happy to settle for a narrow victory.
Opta stats
- Chelsea have won eight of their last 10 games in the Premier League (D1 L1), including each of the last five at Stamford Bridge.
- Southampton are winless in their last six Premier League away games, drawing two and losing four.
- Marcos Alonso has had a hand in 14 goals since his Chelsea debut (10 goals, four assists); more than any other Premier League defender.
- Only Alvaro Morata (49) has attempted more shots in the Premier League for Chelsea this season than Alonso (34).
- Chelsea have scored seven direct free-kicks under Antonio Conte in all competitions, more than any other Premier League side since the start of last season.
- Southampton have made 25 changes to their starting XI over their last five Premier League games - in their previous 13 games this season they made 21 changes.
Man of the match - Marcos Alonso
The Spaniard has been outstanding for Chelsea this season and this was another eye-catching performance from the left wing-back. His winner was his fourth goal of the season, making him the joint-top scoring defender in the Premier League.
He could have had more, too. Alonso repeatedly got himself into dangerous positions and attempted six shots in total - twice as many as any other player on the pitch. He did not have too much to do defensively, but his attacking contribution was invaluable.
The only downside was the yellow card which will keep him out of next weekend's meeting with Everton.
The pundit - Charlie Nicholas
"Southampton did not set up too badly in the first 10 minutes. Bertrand got up and down the left hand side well. But then Cedric got injured. They didn't change the formation after Lamina came on but they're camped in again. They had all nine players just sitting in front of their box, the official parking of the bus, and they never really got going again.
"Alonso's free-kick is a good free-kick. In fact it's better than good because it's right into the post. But I think the goalkeeper expects Willian to take it with his right foot. Alonso looks like he's about to jog over it and he takes it by surprise, and that's enough to give it that distance into the corner."
The managers
Antonio Conte: It was a difficult game. I think when you don't score the second goal you have to suffer because you are afraid. A corner, a free kick, and your opponent can score. I think that we dominated the game. We shot 28 times but only eight on target and one onto the post. I think we have to score the second goal to be more relaxed."
Mauricio Pellegrino: "Obviously when you are playing with five defenders you don't have a lot of people in the middle and they managed more of the ball. When you win something on one side you always lose something on the other, but at the end we had a couple of chances and we were really close. The feeling wasn't bad because we were fighting until the end and we were close to equalising."
What's next?
Chelsea face Bournemouth in the EFL Cup on Wednesday before their trip to Everton next weekend, while Southampton's next game comes at home to Huddersfield in the Premier League on Saturday.