SOUTH African Wynand Olivier is a major doubt for Worcester Warriors’ Midlands derby against Aviva Premiership high-flyers Wasps at Sixways on Saturday (3pm).

The 32-year-old centre suffered a hamstring injury in the second half of Warriors’ 50-12 battering at Exeter Chiefs at the beginning of this month.

Warriors director of rugby Dean Ryan says prop Nick Schonert and flanker Phil Dowson have passed head assessment protocols and he’s hopeful skipper Gerrit-Jan van Velze (toe) will be fit.

Fijian lock Tevita Cavubati is available for selection after serving a nine-week ban for biting an opponent in Warriors’ defeat at London Irish in January.

With Warriors safe from relegation, Ryan is determined not to allow their season to fizzle out with tough fixtures remaining against Wasps, Leicester Tigers and Saracens.

“Wynand is the biggest concern for his hamstring pull against Exeter so we might look to reshuffle the backline to look at some different options,” said Ryan.

“We want to go as strong as we can but looking at options might be something we will do.

“What I don’t want to do is to go into next year still wondering so I think we might have a look at some different things.”

Wasps are third in the table and reached the semi-finals of the European Champions Cup after a thrilling last-gasp 25-24 win against Exeter last weekend.

Warriors, who are 10th, have triumphed in their last three home matches but have not won four in a row at Sixways since December 2012.

Wasps’ only defeat in their last 12 matches was at Gloucester last month and they have won their last three games against Warriors. Wasps have triumphed on three of their last four visits to Sixways.

Ryan said: “We’ve had a week to re-charge the batteries and I think we’re in a much better place as a squad and I am looking forward to the next four weeks.

“It’s pretty clear we have got challenging opposition – three of the best sides in Europe if you look at the statistics and it’s going to be a massive challenge but that’s exactly what we want.

“We have got some injuries but I want to try some different things but more importantly we must have the energy to compete with these guys.”

Wasps are playing some exciting, running rugby and scored two late tries against Warriors earlier in the campaign to seal a remarkable 32-22 victory at the Ricoh Arena.

Ryan said: “Wasps are a massively physically side and I thought the game between them and Exeter was probably one of the best I have seen in Europe for some time.

“We are aware of the challenge but that’s what we want to face up to."

Ryan added: “It will be interesting to see Wasps do. They have got a lot happening over the next few weeks – with the Premiership play-offs and the Champions Cup. But they have a pretty decent squad with a lot of layers."