(CNN) -- Andy Murray, Nikolay Davydenko and Jo-Wilfried Tsonga have all crashed out in the last 16 of the Dubai Championships as Wednesday produced a day of shock results.

Third seed Murray, playing in his first tournament since losing to Roger Federer in the final of the Australian Open, was bundled out by Serb Janko Tipsarevic in a match lasting two-and-a-half hours.

Murray, 22, looked to have rescued things after dropping the opening set -- but he eventually lost 7-6 4-6 6-4.

Fourth seed Nikolay Davydenko struggled to win his opening match on Tuesday because of a wrist injury and he was forced to withdraw from his match with Michael Berrer after losing the first set 6-3.

And fifth seed Tsonga made it a treble of seeds to fall when he found Croat Ivan Ljubicic too hot to handle in the humid conditions, bowing out 7-5 6-3.

However, defending champion Novak Djokovic is through to the quarterfinals after recovering from the loss of the opening set against fellow-Serb Viktor Troicki.

The second seed eventually went through 3-6 6-4 6-2 in a match that lasted just over two hours.

Elsewhere, sixth seed Marin Cilic saved three set points in the second set tie-break to see off Austrian Stefan Koubek 6-2 7-6, while seventh seed Mikhail Youzhny beat Germany's Bjorn Phau 7-6 and will now face Tipsarevic.