Chelsea provisionally moved 13 points clear of Tottenham Hotspur and Manchester City ahead of today's games.
It looked like the flawless opportunity to deliver a cross, but Willian had other ideas and whipped his free-kick around the two-man wall and past Lee Grant, who should have done better than to just help the shot on its way in.
Bournemouth achieved back-to-back wins for the first time in a year thanks to Benik Afobe's two strikes, with the first deflecting off Alfie Mawson.
The England defender made amends in the 87th minute with a deserved victor and, after Phil Bardsley had been sent off for Stoke in added time, Conte celebrated with his staff on the touchline as Chelsea moved on to 69 points, leaving all the pressure on their nearest pursuers who play on Sunday.
On the game itself, Conte observed: "For sure, an important win against a strong team".
Moments after Willian's goal, in protest at another tussle that sent him to the floor, Costa exploded at referee Anthony Taylor.
"It is Chelsea's title now and you could see from their celebrations we ran them close", Hughes said in quotes reported by the BBC.
Craig Dawson scored two headers at The Hawthorns as West Brom condemned Arsenal to a sixth defeat in nine games in all competitions.
"I want that from my players and that behaviour from my players". Costa was far more restrained and refined after the break, holding up play intelligently and providing a platform for teammates to shine.
Not even that could improve Costa's demeanour, though.
Frustrations then boiled over for Bardsley, who was given a second booking for a clumsy foul on Fabregas, as Chelsea ground out a huge win in the race for the title.
The Potters goalkeeper admitted he had made an error for the Blues' opening goal at the bet365 Stadium on Saturday as the home side slipped to a narrow 2-1 loss to the league leaders.
"I said 15 minutes before the game, you've got to book him before he leaves the dressing room", Langley said. But it soon became clear that Mark Hughes wanted his players to hassle Chelsea all over the pitch, led by the more mobile Walters and Saido Berahino.
There was slight confusion between Cahill, Walters and Thibaut Courtois, with the Stoke player going down.
Stoke drew 0-0 with Manchester City last time out, and are one of the few teams to have really tested Chelsea this season.
That hasn't stopped Chelsea fans from panicking though...