Barcelona twice threw away the lead to draw 3-3 at Levante on Tuesday in a potentially fatal blow to their chances of winning the La Liga title.
The draw took Barca into second place in the standings on 76 points, one behind leaders Atletico Madrid and one ahead of third-placed Real Madrid, who both have a game in hand.
Lionel Messi put a dominant Barca in front after 26 minutes and then played a part in Pedri tapping in their second goal in the 34th after a sweeping team move.
Levante got a foothold in the game with a header from Gonzalo Melero in the 57th and talismanic forward Jose Luis Morales equalised three minutes later.
Ousmane Dembele restored Barca's lead in the 64th and looked to have sent Ronald Koeman's side provisionally top of the standings but Levante came back at them and equalised again when striker Sergio Leon netted at the near post in the 83rd.
Atletico can go four points clear of the Catalans with victory at home to Real Sociedad on Wednesday, while Real Madrid visit Granada on Thursday.
"This feels terrible, it's very difficult (to win the title) now," said Barca midfielder Sergio Busquets.
"We wanted to win and put pressure on the other teams but weren't able to and errors cost us dear, as has happened too many times this season. Teams keep scoring too easily against us."
Barca had clawed their way back into the title race with a sensational run of results since January but their resurgent challenge has unravelled in their last four games, in which they have taken five points.
Koeman's side gave away the lead in a shock 2-1 loss to visiting Granada on April 29 and after beating Valencia 3-2 in their next game were held 0-0 at home by Atletico on Saturday, missing a chance to go above Diego Simeone's side in the table.
Busquets, who wore a protective mask against Levante after sustaining a head injury versus Atletico, admitted Barca's opportunity to win the title had practically gone.
"We have very few chances of winning the league now and it's all our fault, we made lots of errors with our positioning and we lost concentration" he added.
"It wasn't just tonight, we've let a lot of points slip away from us this season, too many to fight to win the league."
Elated Sporting fans celebrate first Portuguese title in 19 years
Thousands of emotional Sporting fans shook off the pandemic blues and took over Lisbon's streets on Tuesday evening to celebrate their club being crowned Portuguese champions for the first time in nearly two decades.
Minutes after the end of the match, elated fans outside the Sporting stadium, where their team beat Boavista 1-0, jumped with happiness, hugged, waved flags and shouted "Champions!" as hundreds of cars beeped their horns in celebration.
Sporting striker Paulinho struck the only goal of the game in the 36th minute by sliding in to meet a Nuno Mendes cross and steer the ball into the roof of the net.
Ruben Amorim's side saw out the win to claim the club's 19th league title and end rivals Porto and Benfica's 19-year stranglehold on the championship.
Sporting, who are still unbeaten with two games left, have 82 points after 32 matches, an unassailable eight-point advantage over second-placed Porto.
For some younger fans amongst the huge gathering it was the first time they had experienced their club winning the title.
"It is an incredible happiness that cannot be explained," overjoyed 20-year-old Diogo Carregosa told Reuters. "I waited a long time for this moment."
No fans were allowed to enter the ground due to coronavirus restrictions. Outside the stadium and around Lisbon some supporters ditched face masks, while maintaining social-distancing became close to impossible as more people showed up.
Police had warned fans not to gather in large groups and urged them to practice social distancing and wear a mask at all times, with spokesman Domingos Antunes saying he hoped the celebration would not turn into a "nightmare".
Portugal captain Cristiano Ronaldo, who plays for Juventus, took to social media to congratulate Sporting, where he began his career. "Many congratulations champions," he wrote on Instagram.
Nayara, a 24-year-old Sporting fan, teared up as she said: "Sporting won the championship in the year I started school and today, when I finish my studies, Sporting are champions again...19 years is a long time. It is a dream."
Sporting’s relentless campaign was hard to envisage when they finished fourth last season, 22 points behind champions Porto, and were struggling to fill the hole left after talismanic captain Bruno Fernandes joined Manchester United.
The title win completed a huge turnaround in fortunes for the club three years after the squad was attacked by angry fans at the training ground.
Napoli thrash Udinese to close in on top-four finish in Serie A
Napoli climbed into second place in Serie A and moved a step closer to Champions League qualification with a 5-1 win at home to Udinese on Tuesday.
Gennaro Gattuso’s side are on 73 points, one above Atalanta and AC Milan and four ahead of fifth-placed Juventus.
However, all three of those teams have the chance to make up ground on Wednesday when they face Benevento, Torino and Sassuolo respectively.
Udinese goalkeeper Juan Musso blocked a Victor Osimhen shot from close range after 29 minutes but could do nothing to stop Piotr Zielinski from firing home the rebound.
Fabian Ruiz doubled the hosts' lead two minutes later with a whipped shot into the top corner from edge of the area, but Stefano Okaka pulled one back for the visitors before halftime.
Hirving Lozano pounced on a slack pass from Musso to fire home Napoli’s third after 56 minutes, and they made it four when Giovanni Di Lorenzo tucked in a close-range finish.
Lorenzo Insigne was denied by the cross bar with a fierce shot, but eventually got a goal in stoppage time when he volleyed into the bottom corner.
The result extended Napoli’s unbeaten league run to seven games and leaves them in a strong position to seal a top-four finish in their remaining two games of the season against Fiorentina and Hellas Verona.