The contest for the Premier League's Champions League qualification places got a whole lot more interesting on Saturday after 10-man Chelsea were surprisingly beaten 5-2 at home by relegation-threatened West Bromwich Albion.
Starting the day in fourth place and two points ahead of West Ham United, Chelsea had to play for over an hour with 10 men after Thiago Silva was sent off.
Despite that numerical disadvantage, Christian Pulisic put Chelsea ahead, but two goals from Costa Pereira -- both in first-half stoppage time -- ensured the visitors were ahead at halftime.
A brilliant volley from substitute Callum Robinson extended West Brom's lead and then Mbaye Diagne's fine finish added a fourth, before Mason Mount's tap-in reduced the deficit.
That was the 59th goal in 30 games that West Brom have conceded in the league this season but the visitors didn't panic and Robinson netted his second with a deft finish in the game's final minutes.
The win keeps West Brom's survival hopes alive and moves Sam Allardyce's team onto 21 points, seven behind fourth from bottom Newcastle United.
"It's an unbelievable day," Robinson told BT Sport; "It's been a tough season but it's nice to come here and get so many goals and really enjoy it. It's a good day all round."
'It was not our day'
Silva's red card was the game's turning point, according to Tuchel.
"After that we were unable to cope with the situation," TucheI told BT Sport. "I don't know why.
"We gave away two very easy goals. What could go wrong went wrong after the red card. We have to accept the big loss. We did big mistakes before the two yellow cards. There were too many easy ball losses. It was impossible for us to accept the situation," added Tuchel.
"Every shot was a goal from them. Clearly it was not our day today. We will get the right response. First of all it's important we digest it. I did not see it coming, now we have to take our responsibilities -- me included -- and shake it off."
Robinson has scored five goals in the Premier League this season and remarkably they've all been against Chelsea. The game between the two teams in September at West Brom's Hawthorns stadium ended 3-3 after Chelsea had fought back from 3-0 down.
"We're really pleased and satisfied how the players applied our tactics and how we set out to control Chelsea's attacks," West Brom manager Sam Allardyce told BT Sport. "I have to say because we ended up so good in possession and the quality of finishing, it gave us a thoroughly deserved victory.
"People will always look to fact they went down to 10 men. But I thought we started the game brightly and created chances. I thought Thiago Silva was lucky to stay on after the first foul," added Allardyce.
"Our goals were all quality goals -- not just the finishing but the build ups. It's just a a bit of a shame we didn't show that quality in some others games. But this still gives us a bit of hope."