MADRID, Feb. 3 (Xinhua) -- Athletic Bilbao coach Ernesto Valverde has to deal with a defensive crisis as his side prepares for Wednesday's Copa del Rey quarterfinal away to Valencia with none of the team's five specialist central defenders available.

Spain international Dani Vivian and Aymeric Laporte are both out with muscle injuries, while Unai Egiluz still has to play this season after tearing his cruciate knee ligament in the summer.

Yeray Alverez still has two months to serve on a 10-month ban for using a product to prevent hair-loss which contained a prohibited substance and although he was able to resume training with the rest of his companions on Monday, he still can't play until April.

Finally, Aitor Paredes has a one-game ban after his red card in the 4-3 win away to Cultural Leon is the last round.

Valverde has been using left back Yuri Berchiche as a makeshift central defender in recent games such as Sunday's 1-1 draw at home to Real Sociedad, but will have to decide whether to use a player from the club's B-team (which plays in the third tier of the Spanish game) or use Inigo Lekue out of position.

Valverde's injury worries don't end there, with midfielder Benat Prados out for the season with another knee ligament problem while forward Maroan Sannadi is also unlikely to return for at least another month after a knee operation and midfielder Oihan Sancet has a hamstring injury that he picked up last week against Sporting Clube de Portugal.

There are also worries about Spain international winger, Nico Williams after the younger of the Williams brothers has failed to recover from the pubalgia that has troubled him since the closing months of last season.

Club and player decided against an operation in the summer and opted for a more conservative treatment, but that has not given the desired results and Nico still looks considerably below his best with reports that the club is considering a new treatment that could sideline him for up to two months.

If that treatment works it should mean Nico is fit for the World Cup, but with Athletic Bilbao just three points above the relegation zone and vital league matches against Levante and Oviedo after the visit to Valencia, the feeling is the issue should have been dealt with much sooner.