MADRID (AP) -- Atletico Madrid's attention will return to domestic affairs, as it looks to defend its lead at the top of La Liga, with the club closing in on its first league title in 18 years.
Atletico has a tough trip to Valencia on Sunday, three days before it plays the return leg of its Champions League semifinal at Chelsea. Before it can focus on securing a place in the May 24 final in Lisbon, the league leader must maintain its slim advantage over Barcelona and Real Madrid.
Madrid, which has a game in hand on the leader, faces Osasuna on Saturday while Barcelona looks to stay focused on winning the only trophy up for grabs when it travels to Villarreal a day later.
With four games to play, Atletico leads with 85 points, Barcelona has 81 points, and Madrid has 79 points. Atletico will secure the title by winning three of its final four matches.
Here are five things to know about La Liga this weekend:
COURTOIS' CHELSEA EFFECT
Atletico Madrid's scoreless draw against Chelsea opened up further discussion about the future of goalkeeper Thibaut Courtois.
The Belgium international is on-loan from Chelsea, which lost regular Petr Cech to injury during Tuesday's match. Cech's absence means 41-year-old backup Mark Schwarzer is Chelsea's No. 1 'keeper for the rest of the season, a situation manager Jose Mourinho likely pondered while watching Courtois on Tuesday.
Courtois has been one of the pillars to Atletico's success and the club is hopeful of extending the loan-deal for a fourth season.
"It's better not to think about it and to focus on just playing," said Courtois, who is on course for winning the league's Zamora trophy for the goalkeeper who concedes the fewest goals in a season.
GOOD NEWS FOR BARCA
Barcelona finally received some good news this week when FIFA temporarily lifted a transfer ban, so the club can complete a reported deal with goalkeeper Marc Andre Ter Stegen.
With the club on the verge of improving Lionel Messi's current deal, talk has already begun over which players will exit this summer.
The Catalan club -- on the verge of its first trophyless season since 2007 -- needs to bolster its defense, and Dani Alves' future is a big uncertainty with the Brazil international out of contract this summer.
Barcelona labored to victory over Athletic Bilbao on Sunday and can ill-afford a repeat knowing a league trophy will be impossible if it drops any more points before the season finale against Atletico.
Cristiano Ronaldo returned for Real Madrid's 1-0 Champions League win over Bayern Munich but the Portugal forward showed some rust after a four-game layoff to a leg injury.
Coach Carlo Ancelotti said Ronaldo would be available for Saturday's match against Osasuna despite the Champions League semifinal return in Germany three days later, while Gareth Bale should also start after battling the 'flu this week.
Ronaldo leads the league with 28 goals.
CHAMPIONS LEAGUE ON THE LINE
Athletic Bilbao can just about secure its return to the Champions League for the first time since the 1998/99 season with a victory against Sevilla on Sunday.
Fourth-place Athletic, which fields only Basque players in its team, is three points up on Sevilla, which has won nine of its last 10 league matches to suddenly threaten for the final qualifying spot for next season's Champions League.
Athletic will have the benefit of a full week off with Sevilla playing Valencia in the Europa League on Thursday.
"We're a team that won't settle for a draw, we always go out looking for victory," defender Mikel San Jose said. "A draw wouldn't be a terrible result but we're only thinking about the win."
While Athletic and Sevilla battle for fourth, Real Sociedad and Villarreal look likely to occupy Spain's final pair of European qualifying spots with the clubs set to take part in the Europa League next season.
Barring a victory against sixth-place Sociedad, last-place Real Betis will become the first team to be relegated this season.
There are six teams within seven points of each other in the relegation race, with Almeria and Getafe currently the other two teams set to drop out of the top flight division.
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