Substitute Danny Welbeck scored a dramatic stoppage-time equaliser for Brighton to deny Chelsea victory and deal a blow to their hopes of keeping pace with Manchester City at the top of the Premier League.
Chelsea looked set to move three points clear of fellow title contenders Liverpool when Romelu Lukaku marked his first top-flight start for two months by giving his side a lead, which they held until the 91st minute.
Brighton carved out 18 chances in total at Stamford Bridge but looked set for disappointment before Welbeck met Marc Cucurella's chipped cross.
On a bad night for Chelsea, they also lost defenders Reece James and Andreas Christensen to injury.
More to follow
Player of the match
WelbeckDanny Welbeck
Chelsea
Squad number9Player nameLukaku
Squad number19Player nameMount
Squad number7Player nameKanté
Squad number16Player nameMendy
Squad number2Player nameRüdiger
Squad number28Player nameAzpilicueta
Squad number24Player nameJames
Squad number4Player nameChristensen
Squad number14Player nameChalobah
Squad number10Player namePulisic
Squad number8Player nameKovacic
Squad number20Player nameHudson-Odoi
Squad number3Player nameAlonso
Squad number5Player nameJorginho
Brighton & Hove Albion
Squad number18Player nameWelbeck
Squad number8Player nameBissouma
Squad number3Player nameCucurella
Squad number2Player nameLamptey
Squad number14Player nameLallana
Squad number20Player nameMarch
Squad number33Player nameBurn
Squad number34Player nameVeltman
Squad number10Player nameMac Allister
Squad number17Player nameAlzate
Squad number1Player nameSánchez
Squad number12Player nameMwepu
Squad number15Player nameModer
Squad number9Player nameMaupay
Line-ups
Chelsea
Formation 3-4-2-1
16Mendy
28Azpilicueta4Christensen2Rüdiger
10Pulisic8Kovacic5Jorginho24James
19Mount20Hudson-Odoi
9Lukaku
16Mendy28Azpilicueta4ChristensenSubstituted forChalobahat 45'minutes2RüdigerBooked at 41mins10Pulisic8KovacicBooked at 58mins5Jorginho24JamesSubstituted forAlonsoat 27'minutes19MountBooked at 81mins20Hudson-OdoiBooked at 64minsSubstituted forKantéat 67'minutes9LukakuSubstitutes
1Arrizabalaga3Alonso7Kanté14Chalobah17Saúl18Barkley22Ziyech29Havertz31SarrBrighton
Formation 3-4-2-1
1Sánchez
34Veltman33Burn3Cucurella
2Lamptey14Lallana8Bissouma20March
15Moder10Mac Allister
9Maupay
1Sánchez34Veltman33Burn3Cucurella2LampteySubstituted forMwepuat 66'minutes14Lallana8BissoumaBooked at 81mins20March15ModerSubstituted forAlzateat 88'minutes10Mac AllisterSubstituted forWelbeckat 80'minutes9MaupaySubstitutes
4Webster12Mwepu13Groß17Alzate18Welbeck23Steele24Duffy30Richards58FergusonReferee:Mike DeanAttendance:40,080Live Text
Match ends, Chelsea 1, Brighton and Hove Albion 1.
Second Half ends, Chelsea 1, Brighton and Hove Albion 1.
Goal! Chelsea 1, Brighton and Hove Albion 1. Danny Welbeck (Brighton and Hove Albion) header from the centre of the box to the bottom left corner. Assisted by Marc Cucurella with a cross.
Joël Veltman (Brighton and Hove Albion) wins a free kick in the defensive half.
Foul by Mason Mount (Chelsea).
Foul by Steven Alzate (Brighton and Hove Albion).
N'Golo Kanté (Chelsea) wins a free kick in the defensive half.
Substitution, Brighton and Hove Albion. Steven Alzate replaces Jakub Moder.
Attempt missed. Mateo Kovacic (Chelsea) right footed shot from outside the box misses to the left following a corner.
Corner, Chelsea. Conceded by Dan Burn.
Attempt missed. N'Golo Kanté (Chelsea) right footed shot from the right side of the box misses to the left. Assisted by Romelu Lukaku.
Attempt missed. Romelu Lukaku (Chelsea) left footed shot from the centre of the box misses to the left.
Attempt blocked. Joël Veltman (Brighton and Hove Albion) right footed shot from outside the box is blocked. Assisted by Yves Bissouma.
Yves Bissouma (Brighton and Hove Albion) is shown the yellow card.
Mason Mount (Chelsea) is shown the yellow card.
Offside, Chelsea. César Azpilicueta tries a through ball, but Romelu Lukaku is caught offside.
Substitution, Brighton and Hove Albion. Danny Welbeck replaces Alexis Mac Allister.
Corner, Chelsea. Conceded by Marc Cucurella.
Attempt blocked. Mason Mount (Chelsea) left footed shot from outside the box is blocked.
Attempt saved. Trevoh Chalobah (Chelsea) header from the centre of the box is saved in the top centre of the goal. Assisted by Mason Mount with a cross.
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