Real Madrid dropped points for the third time in seven games since Zinedine Zidane's return as they were held to a 0-0 draw away to Getafe in La Liga on Thursday, which harmed their neighbours' hopes of a top-four finish.
The draw left third-placed Real an embarrassing 15 points behind runaway leaders Barcelona and six back from second-placed Atletico Madrid after 34 games.
Getafe, who have never played in the Champions League, clung on to fourth spot but are level on 55 points with Sevilla, who thrashed Rayo Vallecano 5-0 earlier on Thursday.
Zidane again made several changes to his side as he prepares to shake up the squad ahead of next season after a woeful campaign on all fronts, starting without Marcelo, Luka Modric, Toni Kroos and Marco Asensio
Teenager Brahim Diaz was Real's liveliest performer in what was another underwhelming performance from the deposed European champions, who needed goalkeeper Keylor Navas to make an impressive double save to thwart Jaime Mata in the second half.
Getafe had a half-hearted penalty appeal waved away late in the game when Mata went down after a challenge from Dani Carvajal in an end-to-end finish to what was a scrappy encounter with few clear chances.
Title homecoming awaits untouchable Barcelona
Barcelona can clinch the Liga title with victory at home to relegation-threatened Levante on Saturday -- the first step in what they hope will be a clean sweep of trophies this season.
Ernesto Valverde's side are nine points clear of Atletico Madrid with each club having four games left and Barca, who have the better head-to-head record, could be champions before kick off at the Nou Camp if Atleti lose at home to Real Valladolid.
Should second-placed Atletico draw, a point against Levante would be enough for Barcelona to guarantee their 26th league title and eighth in 11 years.
Barca captain Lionel Messi will be able to lift the trophy in front of their supporters after Spanish federation president Luis Rubiales said the team would be handed the silverware on Saturday, instead of at their final home game of the campaign.
Messi will join a select group of players to have won 10 league titles with one club, while midfielder Arturo Vidal will collect an eighth consecutive title since 2012 after winning four championships with Juventus and three with Bayern Munich.
The Catalans began the season by winning the Spanish Super Cup and, assuming they win the league, could lift a third domestic trophy when they face Valencia in the Copa del Rey final on May 25.
The prize they covet most though is the Champions League, which Real Madrid have dominated in the last three seasons, especially with the final taking place in the Spanish capital.
Valverde can afford to rest players against Levante ahead of next week's Champions League semi-final first leg at home to Liverpool, which will provide the high watermark of a season in which no-one has come close to challenging his side in La Liga.
Barca have led from the front since early December, when they crept ahead of Sevilla and Atletico as Real Madrid endured a nightmarish season and were not considered realistic title rivals until a burst of form in February.
Barca soon knocked their biggest rivals back out of the title race though by marching 12 points clear of them with a 1-0 victory at the Santiago Bernabeu in March.
Atletico could not be written off until Barca overpowered them in April with a 2-0 win which took the Catalans 11 points clear at the top and began a procession towards retaining the title, which they also won at a canter last season.
"We're very happy with how we've worked throughout the season, now we cannot wait for Saturday so we can become champions at our home in front of our fans," said Sergio Busquets after Barca's 2-0 win at Alaves on Tuesday.
"What we have done in the last few years is historical."
Barca have only lost twice this season, with their last defeat coming in early November at the hands of Real Betis.
"We deserve this title, we have been the best team throughout the season," added Barca midfielder Carles Alena.
On Sunday, Real Madrid make the short trip to struggling Rayo Vallecano, while Getafe visit Real Sociedad in their bid to secure a top-four finish for the first time.
Gomez strike sends dark horses Atalanta to Coppa Italia final
Surprise package Atalanta reached the Coppa Italia final for the first time since 1996 when an Alejandro Gomez strike gave them a 2-1 win over Fiorentina in their semi-final second leg on Thursday.
The Argentine's low drive from the edge of the area was fumbled by goalkeeper Alban Lafont in the 69th minute as Atalanta completed a 5-4 aggregate win to continue their remarkable season.
Luis Muriel put Fiorentina ahead after three minutes, slipping the ball past Pierluigi Gollini after being sent clear by Federico Chiesa's incisive pass.
Atalanta levelled 11 minutes later, Josip Ilicic converting a penalty after Gomez went down under a challenge from Federico Ceccherini.
Atalanta, who will meet Lazio in the final on May 15 in Rome, have won the competition once, in 1963 -- the Bergamo club's only major trophy. Fifth in Serie A, they are also challenging for a place in next season's Champions League.
The defeat effectively ended Fiorentina's season as they are 11th in Serie A with no realistic chance of qualifying for Europe and are under no threat of relegation.