Chelsea came from two goals down to rescue a 2-2 draw against Tottenham Hotspur at Stamford Bridge and crown Leicester City as Barclays Premier League champions.
Mauricio Pochettino's men needed victory to retain hope of stopping Leicester's astonishing march towards glory and Harry Kane's 25th BPL goal of the season, along with a clinical finish from Son Heung-min, gave them a healthy half-time advantage.
In a feisty encounter played at a pulsating pace, Gary Cahill reduced the arrears in the 58th minute and Eden Hazard, who schemed menacingly as a half-time substitute, scored his first league goal at Stamford Bridge since last season's title-clinching win over Crystal Palace to ensure a new and unlikely name would be etched on the trophy.
Former Chelsea manager Claudio Ranieri will hoist that silverware at a raucous King Power Stadium after Saturday's match against Everton, no doubt thrilled by the help from his former employers.
Cahill and John Terry were reunited at the heart of the Chelsea defence, with the former heading a fourth-minute corner wide as the hosts applied early pressure.
Cesc Fabregas, the former Arsenal midfielder, was picked out by Costa and dragged wastefully wide in the 27th minute.
Spurs spurned a similarly inviting opening with Son, in for the suspended Dele Alli, lashing past the near post but Pochettino's side crafted a fine opener 10 minutes before half-time.
Christian Eriksen combined with Erik Lamela for the Argentina international to pick out Kane's perfectly timed run, with the England striker able to coolly round Asmir Begovic and slot into an unguarded net.
Costa engineered space on the edge of the box to fire over as Chelsea sought a response but they were left with a mountain to climb by a blistering Spurs counter-attack.
Kane intercepted a stray pass from Branislav Ivanovic and Eriksen expertly slid a pass through to Son, whose aim was true this time.
The half ended an altercation after Danny Rose rashly fouled Willian, and both players were booked for their troubles and renewed acquaintances early in the second half as the Brazil winger crashed into his opponent before Son clipped the loose ball wide from the edge of the box.
Chelsea grasped a lifeline in the 58th minute as Spurs midfielder Eric Dier missed an attempted clearance from Willian's corner and Cahill pounced with an emphatic left-footed volley.
The complexion of the contest changed entirely, Hazard to the fore for the hosts, and Willian shot too close to Spurs goalkeeper Hugo Lloris from a Costa pass.
Spurs right-back Kyle Walker was grateful to see Hazard's low cross spin off his shin and wide in the 74th minute, while substitute Ryan Mason shot tamely at Begovic when he should have restored the two-goal cushion.
Despite his misfiring campaign, Hazard showed why he has a more renowned eye for goal from midfield as he darted towards the area, exchanged passes with Costa and found the top corner to break Spurs hearts and spark celebrations in Leicester.
The Chelsea faithful delighted at their team’s fightback, and will now offer a guard of honour to Leicester on the final day.