Chelsea and Liverpool were both dealt a significant blow in the Premier League title race as they played out a thrilling and breathless 2-2 draw at Stamford Bridge with Christian Pulisic netting the hosts' equaliser, a result that leaves leaders Manchester City 10 points clear.
In a meeting between second and third that was billed as crucial in the season, with both sides desperate to keep pace with City following their 11-match winning run, it was Liverpool who struck first as Sadio Mane punished Trevoh Chalobah's error to put the Reds ahead in the ninth minute.
The build-up to the match was dominated by the omission of Chelsea striker Romelu Lukaku after he was dropped by manager Thomas Tuchel and although the Blues had made the brighter start, they found themselves two down inside half an hour when Mohamed Salah beat Marcos Alonso and finished past Edouard Mendy from a tight angle.
Mateo Kovacic handed Chelsea a lifeline with a spectacular, dipping volley from the edge of the box that rattled off the post and beat Liverpool's stand-in goalkeeper Caoimhin Kelleher, and United States international Pulisic fired the Blues level on the stroke of half-time with a composed left-footed finish to bring a frantic opening period to a close.
"It was an incredible first half," Pulisic told the BBC after the match. "You feel after we got the momentum and get back 2-2 it's a bit frustrating not to get the winner but probably a fair result in the end."
Liverpool, who were dealing with key absences and were without manager Jurgen Klopp, as well as Alisson, Roberto Firmino and Joel Matip, for the visit to Stamford Bridge after suspected positive COVID-19 tests, had the better of the early second-half chances and Mendy produced a flying save to keep out Salah's lob.
It was Chelsea who finished on top, however, with Kelleher denying Pulisic's half-volley from close range while Antonio Rudiger also headed wide from a corner.
The result is a huge boost to City's chances of defending their Premier League title and leaves Pep Guardiola's side 10 points clear of second-placed Chelsea and 11 ahead of third-placed Liverpool, although the Reds have a game in hand.
Liverpool will play their next two Premier League against Crystal Palace and Brentford without Salah and Mane as they head to the Africa Cup of Nations. The forwards were both crucial to their fast start under assistant manager Pepijn Lijnders, although Mane was perhaps fortunate to escape a red card inside just six seconds when he caught Chelsea captain Cesar Azpilicueta with his arm when challenging for a high ball.
"A clear red," Azpilicueta said afterwards. "I don't mind if it is five seconds into the game it is a red. I don't understand, we have had these kind of decisions the other day. It is a clear red card. We are getting these decisions against us and it can change the way of the game."
It set the tone for a frantic opening to the contest. Liverpool broke through Mane following Chalobah's wayward header, with Rudiger doing enough to challenge Salah as he looked to convert the cut-back from inside the box.
Liverpool were more ruthless moments later, however, as the visitors struck the opening goal. Mane pounced on Chalobah's mistake as the defender ducked to head a low ball, with the Senegal forward skipping past Mendy before firing a finish past the recovering Azpilicueta.
Chelsea, who had made the brighter start, remained on the front foot and Alonso had two chances at the back post. Liverpool's threat came on the break and Mendy was forced into a save to deny Salah after he was played through on goal, although the Egyptian was a yard offside.
But Salah would not be denied for long and the Premier League's top scorer added his 16th goal of the season in the 26th minute. Salah raced to meet a through ball from Alexander-Arnold before feinting around the outside of Alonso and tucking a finish past Mendy at his near post to double Liverpool's lead against his former team.
Salah raced clear again after a first-time pass from Alexander-Arnold but Chalobah did enough to slide in before Azpilicueta blocked his shot as he looked for the far corner.
In a breathless first half, there was still time for a spectacular Chelsea comeback as the hosts struck twice in four minutes at the end of the opening period.
After Kelleher punched a Chelsea free-kick clear, Kovacic produced an outstanding piece of technique to send a first-time volley crashing off the post and into the back of the net from 20 yards to give the home fans hope.
And the roof almost came off Stamford Bridge when Pulisic tucked a wonderful finish past Kelleher to draw Chelsea level in added time, after N'Golo Kante had played the USMNT star through on goal.
Diogo Jota and Mane threatened after the break with runs in behind Chelsea's high line, although the offside flag was up on both occasions, before Mendy produced a stunning save to deny Salah what would have been an incredible second as the contest continued to be played out at a thrilling pace.
Pulisic was caught out by Jota as he tried to deal with a bouncing ball and with Mendy off his line, Salah looked to beat the goalkeeper from 30 yards. Mendy scampered back to make an excellent reaching stop, before he was called into action again to keep out a fierce drive from international teammate Mane.
The 23-year-old Kelleher replied with an instinctive save to keep out Pulisic's rising half-volley from close range, although the goalkeeper would have been beaten had the American found the space to either side of him.
It capped a perfect weekend for leaders City who struck late to defeat 10-man Arsenal at the Emirates on Saturday.
"It is a big gap," Liverpool's Virgil van Dijk said. "They [City] have the title maybe to lose at the moment but anything can happen still. We have been there and gave it away, so anything is possible. We focus on ourselves.
"If you are 2-0 up you don't want to concede that close to half time, give them the momentum to get back into the game, it happened -- a fantastic strike, you have to give [Kovacic] credit. That gives them momentum and they score the second.
"For the outside world it was quite a good game to watch, but we came here for three points and didn't get them."