Croatia's Ljubicic still waiting on doubles partner

ZAGREB, Apr 7 (Reuters) Croatian playing captain Ivan Ljubicic is not sure who will partner him in tomorrow's Davis Cup doubles match against Argentina as Mario Ancic is still struggling to recover from a back injury.

Ancic was sidelined for today's singles and his replacement, the 378th ranked Marin Cilic, was handed a 6-1 6-1 6-2 drubbing by David Nalbandian.

With the quarter-final balanced at 1-1 after the opening day's singles, the outcome of the tie could depend on tomorrow's result. Cilic is standing by to partner Ljubicic.

If Ancic fails to recover from injury, his absence would be a big blow for the champions as he and Ljubicic have a perfect 6-0 Davis Cup doubles record.

''We have until one hour before the match starts (to select the lineup),'' world number five Ljubicic told reporters at a news conference today.

''Obviously, we would all love for Mario to recover as that would boost our chances in the doubles but it will not be easy because he is still in a lot of pain.'' ''Cilic will take Mario's place if he doesn't recover in time.'' Reuters OM VP0143