Oxford United's sorry start to the season took another turn for the worse when their most valuable player, Paul Powell, was ruled out of tomorrow's crunch clash with Cambridge, writes Jon Murray.

Powell injured his right knee at the start of the second half of United's 3-2 defeat at Walsall on Tuesday and there are fears that he has damaged ligaments.

He had a scan on Wednesday and the results of the scan are expected back later today.

"I have my own ideas as to what it is, but I don't want to say until we know for definite with the results of the scan," said United physio Neal Reynolds.

If it is ligament damage, Powell could be ruled out for weeks. Scot Neil McGowan is set to replace Powell at either left wingback or left back according to which system United use at the Manor tomorrow.

Which system they choose will largely depend on whether Jon Shepheard recovers from the strain he picked up at the Bescot Stadium.

Rob Folland, another who could have filled in at left back, is unavailable. He plays for Wales Under 21s in Belarus in the European Under 21 Championship today.

Shepheard is rated 50-50. If the 19-year-old regains full fitness, Oxford will probably keep an unchanged team Powell apart but if he drops out, they may revert to 4-4-2 which could give an opportunity to Peter Fear on the right side of midfield. Dean Whitehead and Paul Tait look like maintaining their central midfield roles and Joey Beauchamp's two goals in midweek have guaranteed him a starting place.

Summer signing Ian McGuckin, who has missed the last three games with a back injury, played for the reserves against Wycombe on Wednesday and could be involved if United switch back to 4-4-2.

Oxford are the only team in the Nationwide League without a point to their name, but assistant manager Mickey Lewis was encouraged by the performance at Walsall, where they came within eight minutes of taking something away from the league leaders.

"If we show the same amount of commitment as we did against Walsall and Wolves, the best two sides we have faced, we'll be OK. We've got to show that against Cambridge."