Atletico Madrid ended the decade-long dominance of Spanish giants Barcelona and Real Madrid by clinching a first La Liga title for 18 years in a thrilling climax to the campaign on Saturday.
A towering Diego Godin header secured Atletico a 1-1 draw against Barcelona that kept them three points clear of the Catalans in second, sparking wild celebrations among the visiting players and fans.
Barca needed to beat Atletico in the final-day showdown to snatch the title away and Alexis Sanchez gave the hosts hope when he rifled home from an acute angle after 33 minutes at a packed Nou Camp.
But four minutes after the break Godin powered home from a corner and Atletico defended robustly to earn the draw they needed and claim their first championship since 1995-96.
The result prompted Barcelona's Argentine coach Gerardo Martino to announce his resignation after just one season in the job.
"The work and effort of this team is the key and nobody makes any compromises. The team understands this," Atletico coach Diego Simeone told a news conference.
"Today will be one of the most important days in the history of the club. To become champions against Barcelona is a great feeling."
Following the final whistle, the Nou Camp crowd applauded the new champions as they celebrated on the pitch.
"This was something unimaginable at the start of the season but totally deserved," Atletico captain Gabi told Spanish television as his delirious team mates celebrated on the pitch behind him.
"We always believed in ourselves, even when we fell behind today," he added.
"It is an honour to be part of this and to be able to compete with the big clubs.
"Let the fans enjoy this now because they deserve it. We will celebrate this great title now and from Monday we will focus on the Champions League which is the priority now."
Atletico, who contest next Saturday's European showpiece against Real Madrid in Lisbon, finished with 90 points, with Barca second on 87 and Real, also with 87, in third.
It is the first time in 10 years that either Barca or Real Madrid did not win the league and Barca finished without major silverware for the first time in six years.
"We had it within our grasp for 45 minutes but all we can do now is congratulate Atleti," Barca playmaker Andres Iniesta told Spanish TV.
"After we went ahead their goal really hurt us and they are worthy champions," added the Spain international.