GLASGOW, Scotland — Andy and Jamie Murray kept Britain alive in its Davis Cup semifinal against Argentina, winning the doubles match in four sets to reduce the titleholder’s deficit to 2-1 on Saturday.

The Murray brothers beat Juan Martin del Potro and Leonardo Mayer 6-1, 3-6, 6-4, 6-4 in front of a rowdy crowd in Glasgow.

The semifinal is extended to the reverse singles on Sunday, when Andy Murray is set to play Guido Pella and del Potro is down to play Kyle Edmund.

“Two-one down is a tough position to be in,” Andy Murray said, “but we are closer than we were at the start of the day and I still believe we can come back.”

Del Potro and Murray were back on court after an epic 5-hour, 7-minute opening singles on Friday, won by del Potro in five sets. Del Potro wasn’t slated to play in the doubles and was a surprise late change by Argentina captain Daniel Orsanic, especially given the player’s injury problems in recent years.

“As soon as we heard Juan Martin was coming in, they showed their cards, that they wanted to finish the tie today,” Britain captain Leon Smith.

The Murrays have a 6-0 record in Davis Cup doubles.

The winner will play either Croatia or France in the final — and it’s likely to come down to the final match, with Murray a heavy favorite to make it 2-2.

“Everyone is tired, it’s that stage of the season,” Smith said. “It’s the same for their team but if there’s somebody you want going out to get the first rubber on the board, it’s Andy Murray.”