Melbourne, Jan 26(Agencies): Last year's finalist Andy Murray dropped his first set of the year and was made to struggle before overcoming Alexandr Dolgopolov to reach the Australian Open semifinals on Wednesday.

The British fifth seed needed 3hr 06min to finally book a place in the last four where he will play either world number one Rafael Nadal or fellow Spaniard and seventh seed David Ferrer in Friday's semifinal.

It took the Scot a set to work out the quirky, 46th-ranked Ukraine's game before he went two sets up and seemingly set for a straight-sets victory.

But Dolgopolov hit back, taking advantage of Murray's errors to win the third set tiebreaker and force the match into a fourth set.

"It was very tough and every point was different, he hits the ball different to a lot of other players and I struggled a little bit with my rhythm early on," Murray said.

"He came back at me well in the third set but I thought I did well enough."

Murray, who lost in three sets to Roger Federer in last year's Australian final, improved his winning streak to eight matches.

"I had to go for my shots a little bit more in the fourth set, I was a little bit tense in the tiebreaker and served a double fault and missed a couple of easy forehands," Murray said.

Murray was broken twice in a gruelling opening set but broke the unpredictable Ukrainian's serve three times to go one set up in 57 minutes.

The puzzled Scot took some time to figure out the free-spirited Dolgopolov, who constantly went for his shots and ran up a stream of errors in the process.

Streaky Dolgopolov hit 21 winners in the opening set, but they were offset by 26 mistakes.

Murray grabbed a vital break in the fourth game of the second set when Dolgopolov casually over-hit a volley, when it was easier to play a routine winner on game point.

The determined Scot tightened up his serving in the second set, playing the percentages and not dropping a point on his opening four service games to take a grip on the match.

Dolgopolov played another erratic game to lose his opening service in the third set, but he broke back in the sixth.

The Ukrainian went on another purple patch in the tiebreaker as Murray made three crucial errors to drop his first set of 2011 and take the match into a fourth set.

Dolgopolov began the fourth set, disastrously dropping his serve, to love and Murray rammed home with another service break to lead 4-0.

The Scot gave one break back with a sloppy game but recovered his consistency to get over the line.