Barcelona beat Osasuna 2-1 on Saturday to open a 14-point gap over Madrid entering Sunday's matches. Anything but a win by Madrid against Barcelona's city rivals would have allowed the Catalan club to celebrate their 29th La Liga title this weekend.
Hansi Flick's side will have the chance to clinch the title next weekend they host Madrid in a "clasico" at the Camp Nou.
Barcelona's lead is 11 points heading into the final four rounds of the campaign.
"We have a big game against a great rival and they have been playing well," Madrid coach Alvaro Arbeloa said.
"It's a special game for the fans, for us. We are going to rest and prepare well for it."
Sunday's result kept Espanyol winless in 17 consecutive games this year, with 10 losses. They sit in 13th place, but just five points above the relegation zone.
It was a hard-fought match until VinÃcius broke the deadlock in the 55th minute after a nice fake move to get past a couple of defenders inside the area. The Brazil forward added to the lead in the 66th with a shot into the top corner after a beautiful back-heel set up by Jude Bellingham.
Elsewhere, a much-changed Rayo Vallecano prepared for their Conference League semi-final second leg against Strasbourg with a 2-0 win at Getafe.
Sergio Camello and Randy Nteka scored in each half for the visitors, while Rayo goalkeeper Augusto Batalla also saved a penalty to lift the team from the Madrid district of Vallecas to 11th.
Fifth-placed Real Betis won 3-0 win at home over last-placed Real Oviedo
Celta Viga moved above Getafe into sixth, boosting their hopes of European qualification with a 3-1 win at home over Elche and leaving the promoted team among a host of clubs still in danger of relegation.