SHANGHAI, Nov 14: Britain’s Andy Murray sent defending champion Roger Federer crashing out of the Masters Cup in a classic encounter on Friday.

Murray came from a set down to win 4-6, 7-6 (7-3), 7-5 after Federer, apparently hampered by a back injury, saved seven match points in a gripping final set.

The result boosts Murray’s chances of winning the eight-man season finale on debut and means France’s Gilles Simon also reaches the last four.

Federer had never failed to reach the Masters Cup semi-finals in seven straight appearances, winning four titles including the last two. The 13-time Grand Slam champion, who was forced out of the Paris Masters with a back strain, needed to beat Murray to stay in the tournament after losing to Simon earlier.

Federer was also weakened by a stomach bug here, but he started in imperious form and snapped up the first break point of the match at 2-1.

However, Murray was not cowed and he immediately broke back after a searing low pass and when Federer miscalibrated a backhand.

The Briton saved more break points when Federer stop-volleyed and rescued an impossible drop-shot, but cracked on set point against his serve.

Murray immediately answered with a break in the next game and another at 4-2, but wasted two set points as Federer broke twice to force a tense tie-break.

With the scores at 3-3, Murray charged ahead and set up three set points with a rare backhand volley before levelling the match at one set each.

Federer twice took treatment for his injured back and he slowed in the third set, using the drop shot whenever possible, and went behind before breaking back with a mighty forehand.

Federer broke again but flailed a smash yards out to bring Murray level 4-4. He saved seven match points in an enthralling 10th game before losing his next serve.

The match was a re-run of this year’s US Open final, which Federer won in straight sets. Murray beat the ex-number one in Dubai this year and at last month’s Madrid Masters.

Federer was hoping to kick-start his campaign to win back the number one ranking here. He has endured a difficult year, losing the top spot after 237 weeks and also his five-year Wimbledon streak to Rafael Nadal.

Earlier, Simon swept aside Czech alternate Radek Stepanek 6-1, 6-4 but could only qualify when Federer lost.

Simon, 23, who won his ticket to the season finale when world number one Rafael Nadal withdrew injured, finished with a 2-1 record in the round robin.

Czech world number 27 Stepanek came in at the last moment as a replacement for injured American Andy Roddick on Wednesday and, with nothing to play for, struggled to contain the dynamic young Frenchman.

Simon claimed the first set when the Czech netted after just 25 minutes and encountered only marginally more resistance in the second.—Agencies