Nikolay Davydenko could be in trouble against Ivo Karlovic in the Qatar Open quarter-finals.

Davydenko is competing in Doha for a seventh attempt at the title. He is a three-time semi-finalist, denied twice by Andy Murray.

Davydenko finished 2009 by winning the ATP World Finals and would have hoped to start 2010 with high expectations of challenging for the Qatar Open title.

However in the off season Davydenko practised for just two weeks before he fell sick. He was still on medication before coming to Qatar so feels he is struggling on some of his shots.

It has not appeared to affect his tennis too much, he has had two very straightforward wins but Karlovic will be different. The giant Croat’s serve will be a handful for an ailing Davydenko.

Davydenko leads the head-to-head 3-1 with a 7-6, 6-3 win over Karlovic four years ago in this tournament but Karlovic will fancy his chances of revenge given Davydenko’s state of health.

Davydenko is a ¼ favourite with Sky Bet while Karlovic is a generous 10/3 with bet365.

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