Barcelona moved four points ahead of Real Madrid atop La Liga. Both teams face Champions League first-leg ties this week, Real visit Arsenal on Tuesday and Barcelona play in Dortmund the following evening.

Barcelona cut open Betis in the seventh minute and Gavi slid the ball past goalkeeper Adrian from inside the six-yard box.

But the hosts were unable to turn a series of lively attacks into goals. Instead the visitors hit back after 16 minutes when centreback Natan Souza escaped the clutches of his defender to head home a Giovani Lo Celso corner.

Barcelona besieged the Betis goal in the second half but were denied by a combination of dogged defending, strong goalkeeping from Adrian and some agonising near misses.

Wojciech Szczesny did not have to make a save until the 88th minute when he turned away a long-range drive by Natan.

With Betis playing for time, Barcelona did not leave themselves exposed to a late counter-attack as they played out a draw that bolstered their lead at the top.

"If we had won we would be further clear, but in the end it's football," Gavi told Movistar.  "The draw leaves a bitter taste, because we were unable to take advantage of the chances we had."

The draw lifted Betis to fifth.

- 'Lots of chances' -

"La Liga is more complicated, but we have to fight until the last game," said Real Madrid coach Carlo Ancelotti.

"They didn't need to do much to score two goals," said Ancelotti. "We took risks at the end and found ourselves hit on the counter-attack.

"We've had deserved defeats this season, but I don't think we lacked attitude today," he added. "It's not a deserved defeat. We created lots of chances but lacked a little effectiveness."

The victory lifted Valencia to 15th, seven points clear of the bottom three.

Real had an early chance to take control when Valencia's Cesar Tarrega was adjudged to have fouled Kylian Mbappe in the penalty area, but Giorgi Mamardashvili saved a weak spot-kick from Vinicius Junior.

It was the Brazilian's second consecutive miss from the spot for Real, after he wasted a Champions League penalty against Atletico Madrid.

Within a minute Valencia went up the other end and won a corner. From it Mouctar Diakhaby outjumped Antonio Rudiger and rocketed home a header.

Real levelled after 50 minutes when Vinicius tapped over the line in a scramble following a Real corner. It was his 104th goal for Los Blancos, matching Brazilian compatriot Ronaldo.

Real gave a lacklustre performance, nevertheless, Mbappe carved out enough chances to win, but wasted opportunities in the 36th, 37th, 48th, 49th and 68th minutes.

Valencia's Georgian goalkeeper Mamardashvili was in imperious form keeping his team in the game until Duro delivered his winner.

Valencia stunned the dominant hosts deep into injury time when a slick countering-attacking move was emphatically finished by Duro from Rafa Mir's cross.

Ancelotti started third-choice 'keeper Fran Gonzalez following injuries to Thibaut Courtois and Andriy Lunin, although the Ukrainian was fit enough to be named on the bench.

In addition to Arsenal, Ancelotti has to focus on the Copa del Rey final against Barcelona on April 26 in Seville.

"The match against Barca in the Copa del Rey will be different; they'll attack more, and we'll have to be better at the back and be effective up front," the Italian said.