Man-of-the-match Diego Costa scored on his return to the Chelsea starting line-up as the Premier League leaders beat Hull 2-0 at Stamford Bridge to go eight points clear.

Costa, who was reportedly involved in a training-ground bust-up last week and the subject of a mega-money offer from China, returned to the starting line-up after missing the trip to Leicester last weekend.

And he netted his 15th Chelsea goal of the season in first-half stoppage time from 12 yards after Victor Moses' cross following a frustrating opening 45 minutes at Stamford Bridge.

Hull were no pushovers, and were denied a penalty when Marcos Alonso kicked the heel of Abel Hernandez, but Chelsea wrapped up the win on 81 minutes through Gary Cahill's header from Cesc Fabregas' free-kick.

The result means Arsenal are currently Chelsea's nearest challengers, as the Blues gained points on Liverpool, Tottenham, Man City and Man Utd this weekend with 16 games remaining. Hull are 19th, two points off safety.

Title favourites Chelsea now face a decisive fortnight as they go to Liverpool on January 31, before hosting Arsenal on February 4.

Costa replaced Willian in Antonio Conte's starting XI, while Hull were unchanged from the win over Bournemouth last week.

Chelsea's star striker nearly scored within 10 seconds, volleying just wide from 20 yards, before Ryan Mason was worryingly stretchered off with a head injury following a clash with Cahill. Mason, who was given oxygen on the pitch, was later taken to hospital by ambulance for further assessment.

The game was delayed for six minutes, and Hull remained solid throughout the first half, with Harry Maguire forcing a decent save out of Thibaut Courtois from long range.

Alonso's deflected effort from the edge of the box forced Eldin Jakupovic to tip the ball over the bar, before Chelsea struck in the seventh minute of added time.

Hull complained that Hernandez had been dragged down by Cahill in the build-up to the goal, which saw Moses' drilled cross converted by Costa with a right-footed, first-time finish into the bottom corner.

Costa celebrated by performing a "chatter" gesture with both hands after a week of heavy speculation surrounding his Chelsea future.

After the break, Hull had a strong appeal for a penalty turned down by referee Neil Swarbrick after Alonso failed to clear and kicked the back of Hernandez's heel inside the box, while Courtois was tested again by a long-range effort from David Meyler.

Courtois then saved from an acute angle after Michael Dawson's half-volley, as Hull arguably had the better of play in the second period.

But Chelsea got their second against the run of play with nine minutes remaining, Cahill heading home unopposed in the area from substitute Fabregas' fine set piece delivery.

Costa nearly bagged a second moments later after being played through on goal by Fabregas, but Jakupovic came out well to block the effort.

Substitute and new Hull signing Oumar Niasse brought a fine save from Courtois late on with a snap-shot from an angle, but Chelsea held on to keep the clean sheet.

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Player ratings

Chelsea: Courtois (6); Azpilicueta (6), David Luiz (6), Cahill (6); Moses (7), Kante (6), Matic (6), Alonso (6); Pedro (6), Diego Costa (8), Hazard (6)

Subs: Fabregas (7), Willian (6), Batshuayi (6).

Hull: Jakupovic (6), Maguire (7), Dawson (7), Davies (6), Elabdellaoui (6), Mason (NA), Huddlestone (6), Clucas (6), Robertson (6), Evandro (6), Hernandez (5)

Subs: Meyler (6), Diomande (6), Marshall, Niasse (6)

Man of the match: Diego Costa

Teams

Chelsea Courtois, Azpilicueta, Luiz, Cahill (c), Moses, Kante, Matic, Alonso, Pedro (Willian 71), Costa (Batshuayi 87), Hazard (Fabregas 71)
Subs Not Used Begovic, Zouma, Ake, Chalobah
Booked Kante
Goals Costa 45+7, Cahill 81

Hull City Jakupovic, Maguire, Dawson (c), Davies (Niasse 59), Elabdellaoui, Mason (Meyler 20), Huddlestone, Clucas, Robertson, Evandro, Hernandez (Diomande 75)
Subs Not Used Marshall, Maolney, Tymon, Bowen
Booked Dawson, Davies
Goals

Attendance 41,605

Referee Neil Swarbrick