Facing the world No. 1 Istomin showed no signs of nerves as he matched the Spaniard game for game until 6-6 and an inevitable first set tie break.

It took a couple of classic Nadal forehand winners and an unreturnable serve to give the No. 1 seed the first set, capturing the tie break 7-4.

Istomin refused to follow the script though and quickly stunned Nadal by breaking his serve in the first game of the second set.

Once the break was secured, there were very few chances for either player and when Istomin stepped up to serve at 5-4 it was crunch time for the world number 72.

Despite a remarkable retrieving winner by Nadal from a drop shot at 30-15 Istomin kept his cool and the crowd cheered and clapped the underdog as he squared the match at one set all.

At the beginning of the deciding set it was clear that the new French Open champion wasn't at his best and he had been forced to call the trainer at the end of the second set. He sent out a scream of frustration in the fourth game as he made yet another unforced error.

The crowd, the majority of whom were wrapped in coats and blankets as the cold London evening set in, did their best to encourage Nadal as the usual cries of "Come on Rafa!" echoed around the stands, but these were matched by enthusiastic "Come on Denis!" cries.

At 3-3 Nadal saved two break points and just one game later, after a world class forehand passing shot and a failed hawk eye challenge by Istomin, Nadal had the crucial break.

The matched look to be all but over until Istomin miraculously saved two match points and broke straight back. The crowd could hardly believe their eyes as Nadal missed a smash on match point.

Champions though are made of sturdy stuff and at 5-4 up with Istomin serving Nadal showed his fighting qualities as he wrapped up the tie in front of an appreciative crowd.

"I finished the match playing better" said the world No. 1 afterwards, "he has a good game for grass, good backhand, serves good, myself [played] worse than last few times."

The top seed will now face his fellow Spaniard, eighth seed Feliciano Lopez, in the quarter-finals tomorrow and Nadal commented on his next opponent and friend, saying, "he is a very good player on grass, good serve."