Madrid: Luis Suarez's 55th-minute goal helped Barcelona beat local rivals Espanyol and in the process Barca kept its title hope alive and send Espanyol to the second division after 26 straight seasons in the top flight.
Real Madrid can reclaim a four-point lead with three rounds left with a home win against relegation-threatened Alavs on Friday. Madrid, seeking its first league title in three years, has a perfect record since the league resumed following the coronavirus break.
"We knew it would be a difficult match because of Espanyol's situation," Suarez said.
"We are going to keep trying to win our matches and see if Madrid falters."
Only a win in the city derby could have kept last-place Espanyol with a chance of staying in the top tier. The club owned by Chinese businessman Chen Yansheng hasn't played in the second division since the 1993-1994 season. It had been among the teams with most consecutive seasons in the top flight, along with Barcelona, Real Madrid and Athletic Bilbao.
"We have to apologise to our fans for what we have made them go through," Espanyol captain Javi Lopez said.
"This is a difficult moment. Nothing went right for us this season. We are committed to coming back stronger."
It was the sixth straight loss for Espanyol, and its 11th consecutive league defeat away to Barcelona at the Camp Nou Stadium. It has 24 points from 35 matches 11 points from safety.
Both teams went a man down to a straight red card early in the second half. Barcelona forward Ansu Fati was sent off after a hard foul on Fernando Calero in the 51st, and Espanyol midfielder Pol Lozano was ejected after a tough foul on Gerard Piqu in the 54th.