Chelsea's lead at the top of the English Premier League was cut to just four points after Manchester United's 2-0 victory at Old Trafford.
With six games remaining, the result will give Tottenham belief it can lift the trophy at the end of May.
Chelsea coach Antonio Conte was under no illusions as to how important each of those games will be.
"We have to think that there are six finals from now until the end," Conte said.
He added: "The league is open and we have a 50% (chance) to win the league."
But Chelsea does have a more favourable run-in than Tottenham.
The only top-six side the Blues have to face is Everton, while Tottenham will take on both Arsenal and Manchester United.
However, the signs against the Red Devils weren't good for Chelsea.
The Blues have been used to dominating games and creating numerous chances in the vast majority of matches this season.
But Chelsea failed to have a shot on target in an EPL game for the first time since September 2007, which also came against United at Old Trafford.
Additionally, their one shot in the first half was the lowest they had mustered in a first 45 minutes this season.
Conte admitted United showed more determination in the match, but he also blamed himself for the defeat.
"They showed more desire, more ambition, more motivation," said Conte.
"It is very simple but in this case the fault is of the coach. It means the coach was not able to transfer the right concentration, desire, ambition to win this game."
"To play this type of game from now and until the end, we must have great enthusiasm, great motivation to try to reach the target."
But for United, it was a massive boost to their top four hopes.
United's controversial openerUnited's controversial opener0:54
The three points took them into fifth spot, four points behind fourth-placed City. However, the Red Devils still have seven matches to play. Only Arsenal have more games left (eight).
The victory ended an eight-match winless run against Chelsea, which was their longest streak without a win against a single opponent.
It also extended the Red Devils' unbeaten streak to 22 games, which was the longest unbeaten run in a single season by a team since United did it in 2010-11.
The importance of the win wasn't lost on former Chelsea coach Jose Mourinho.
"With Liverpool and Manchester City victories, if we don't win then goodbye Premier League," Mourinho said.
"These three points were phenomenal."
Perhaps even more pleasing for Mourinho was seeing his attackers take their chances; especially without Zlatan Ibrahimovic in the line up.
Marcus Rashford and Ander Herrera's goals were scored with United's first shots on target against the Blues.
"The result means we keep two windows open to play Champions League football," Mourinho said.
"I can't give up on the Premier League yet.
"We have to try.
"If one day we are in the Europa League and the distance in the Premier League is too big, then we have to prioritise and nobody can criticise us if we do things in a different way for the final few matches.
"But while it is mathematically possible we have to go with everything we have."
Meanwhile, Liverpool is up to third after a 1-0 win at West Brom.
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