A humming Novak Djokovic made hard work of staying on course to retain his Shanghai Masters title as he fought back to beat Mischa Zverev before Andy Murray found a more straightforward passage into the semi-finals on Friday.

World number one Djokovic has lost his way in the second half of the season and was far from his best in a 3-6 7-6 (7-4) 6-3 victory over qualifier Zverev.

Murray is attempting to replace Djokovic at the top of the rankings before the end of the year and the in-form Brit maintained his impressive form with a 6-2 6-2 success over David Goffin.

Djokovic will face Roberto Bautista Agut in the last four at Qi Zhong Stadium on Saturday after the 15th seed beat Jo-Wilfried Tsonga 6-3 6-4.

Gilles Simon stands in the way of Wimbledon champion Murray and another final following his triumph against Jack Sock in the last quarter-final of the day.

DJOKOVIC PLAYING TO A DIFFERENT TUNE

Djokovic looked short of motivation as he faced the threat of slumping to what would have been a stunning loss to world number 110 Zverev.

The 12-time grand-slam champion was a set and a break down before digging himself out of a hole to avoid an upset.

Djokovic made 37 unforced errors, but the top seed came through another test of character and revealed that humming to music helped him to get the job done.

"It was towards the end of the match. Instead of the occasional tantrum that I used to have, I hope it's behind me, I would switch that vibration and transform it in a tune." he said.

"It wasn't any mantra. It was a famous song actually. I was using it to just forget about my previous mistake. And it worked."
 

IMPERIOUS MURRAY EASES THROUGH

While Djokovic was nowhere near the peak of his powers, Murray goes from strength to strength and Goffin was unable to live with the Wimbledon champion.

Commanding on serve and resolute in defence, the Brit maintained his outstanding form and has now won 16 sets in a row after taking the China Open title last weekend.

A fluent Murray was a man on a mission, breezing into the last four to make it five wins out of five over Goffin and stay in the hunt for a 13th ATP World Tour Masters 1000 title.

Goffin, striving to qualify for the ATP Finals, was unable to break the Murray serve and failed to hold on four occasions in a match which was over in an hour and 35 minutes.

BAUTISTA AGUT EYES DJOK SHOCK, SIMON OUTLASTS SOCK

Bautista Agut moved into only his second Masters 1000 semi-final by coming past ninth seed Tsonga 6-3 6-4.

Two years after his previous semi-final at this level, which he lost to Rafael Nadal in Madrid, Bautista Agut feels he can cause more problems for favourite Djokovic.

"For sure it's a good moment to face him. Novak is one of the best tennis players in history. I played against him a couple of really good matches. I know if I play good I can make it a difficult match for him." said the Spaniard, eyeing his third title of the year after taking his run of wins against Tsonga to three in a row.

Simon came through a topsy-turvy encounter with Sock, who was a break up in the second set after winning the first and also led in a decisive tie-break before the Frenchman prevailed 4-6 6-4 7-6 (7-5).