Davis Cup: Andy and Jamie Murray dig deep to keep defence alive with crucial doubles victory

Having battled it out for five hours and seven minutes in the opening match on Friday, Andy and Juan Martin del Potro found themselves on opposing sides again

The Murray brothers needed every bit of their stamina to prevail (Getty)

Andy Murray dug into his depleted energy reserves to partner brother Jamie to a crucial doubles victory in Great Britain's Davis Cup semi-final against Argentina.

Having battled it out for five hours and seven minutes in the opening match on Friday, Andy and Juan Martin del Potro found themselves on opposing sides of the net once again at Glasgow's Emirates Arena.

This time it was the home hero who came out on top, thanks in no small part to the performance of Jamie, who won his third grand slam title at the US Open last weekend and was the stand-out player on the court.

The 6-1 3-6 6-4 6-4 victory kept Britain in the tie at 2-1 and means a second successive final is still achievable if they can win both singles matches on Sunday.

The pair were given a huge ovation as they prepared to do an on-court interview, and Jamie's voice cracked as he said: "It's not going to get better for me than to play with him in front of a Scottish crowd."

Jamie left the arena on Friday to attend his grandfather's funeral, with Andy forced to miss it to take on Del Potro.

The main question mark going into the second day was whether Andy would deem himself fit enough to play having been unsure how he would pull up.

The back-up option was third singles player Dan Evans, which, for a match Britain had to win, would have been a major gamble.

Andy and Jamie Murray watch the ball closely (Getty)

The big surprise was the presence in the Argentinian team of Del Potro alongside Leonardo Mayer.

With the luxury of a 2-0 lead, the visitors had been expected to rest their best player but his selection was a statement of intent.

The advantage still seemed to be with Britain given the experience of the Murray brothers and Jamie's status as one of the very best doubles exponents in the world.

The 30-year-old was clearly brimming with confidence after his US Open triumph alongside Brazil's Bruno Soares and effortlessly put away a succession of volleys as the brothers raced into a 3-0 lead, winning 10 points in a row.

They wrapped up the opening set after just 26 minutes but a poor game from Andy, including two double faults, gave Argentina the advantage at start of the second.

The brothers were playing together for the first time since a heartbreaking first-round defeat at the Olympics, and a loss on home soil was certainly not a double they wanted.

They pushed again at the start of the third set but failed to convert two chances each on the Del Potro and Mayer serves.

Andy was well below his best level and urged the crowd to provide some much-needed energy.

Del Potro had beaten Murray just 24 hours previously (Getty)

The world number two is renowned for his passion even in straightforward matches and ironically it was going a break down that proved the catalyst for the brothers to turn things around.

When Del Potro landed a return on the line to break Andy's serve for the second time in the match, alarm bells were ringing, but the 29-year-old roared as they broke straight back.

Momentum was with them and a set point on the Del Potro serve was duly taken with a return winner from Andy.

The fourth set was extremely tight, with Jamie needing some treatment on a neck problem that had bothered him since the US Open final.

But the British pair seized their chance with Mayer serving to stay in the match, taking the first of three match points.

Andy will take on Guido Pella in the first match on Sunday, where victory would send the tie into a decisive fifth rubber, probably between Evans and Del Potro.

PA.