Barcelona edged back to the top of La Liga on Saturday night but Iago Aspas's 88th-minute equaliser for Celta Vigo cost them two crucial points as they were held to a 2-2 draw.
Barca were looking to capitalise on playing first, with rivals Real Madrid not in action until Sunday's trip to Espanyol.
A Luis Suarez brace, either side of Fedor Smolov's 50th-minute equaliser, had them on course to do so but Aspas's late free-kick provided what could be a crucial twist in this tight title race.
Elsewhere, goals from Raul Garcia, Oihan Sancet and Asier Villalibre helped Athletic Bilbao to a 3-1 win over Mallorca in the afternoon match.
Atletico Madrid strengthened their grip on third place with a 2-1 win over Alaves thanks to second-half goals from Saul Niguez and Diego Costa, the latter a penalty.
Joselu pulled a goal back for the visitors from the penalty spot in stoppage time.
Enric Gallego struck in the sixth minute of time added on as Osasuna snatched a 2-1 victory over relegation-threatened Leganes. It was Gallego's second of the night after Javier Aviles cancelled out his opener.
Bayern Munich lifted the Bundesliga trophy in an empty stadium as they ended the campaign with a 4-0 win over Wolfsburg.
Kingsley Coman, Mickael Cuisance, Robert Lewandowski and Thomas Muller were all on the scoresheet for the newly-crowned champions.
Chelsea-bound Timo Werner struck twice as RB Leipzig won 2-1 at Augsburg, moving them within three points of second-placed Borussia Dortmund who suffered a shock 4-0 home defeat to Europa League-chasing Hoffenheim.
Andrej Kramaric scored all four goals for the visitors, the last of them a 50th-minute penalty.
Borussia Monchengladbach made certain of the final Champions League spot with a 2-1 win over Hertha Berlin as Jonas Hofmann and Breel Embolo got on the scoresheet.
Werder Bremen thrashed Cologne 6-1 to avoid automatic relegation, a fate suffered by Fortuna Dusseldorf after they were beaten 3-0 by Union Berlin to join Paderborn in the second tier.
Paderborn signed off with a 3-2 defeat at Eintracht Frankfurt, while Bayer Leverkusen beat Mainz 1-0 and Freiburg were 4-0 winners over Schalke.
Lazio cut the gap at the top of Serie A pack to four points as they came from behind for 2-1 win over a Fiorentina side who finished with 10 men.
Franck Ribery put the Viola ahead in the 25th minute, but Ciro Immobile equalised from the penalty spot in the 67th minute before Luis Alberto put Lazio ahead with eight minutes to go.
Fiorentina had Dusan Vlahovic dismissed in stoppage time.
Brescia remain rooted to the bottom of the table after blowing a 2-0 lead in a 2-2 draw with Genoa.
Alfredo Donnarumma and Alessandro Semprini had Brescia 2-0 up inside 13 minutes, but the hosts then conceded two penalties, converted by Iago Falque and Andrea Pinamonti, as Genoa took a point.
Cagliari moved up to 10th with a 4-2 win over Torino.