Lee Jarman's Oxford United career looks to be hanging by a thread after he was the one sacrificed when it all went wrong on the opening day.

The former Cardiff City player started in United's all-new three-man central defence against Peterborough at the Manor on Saturday, but manager Denis Smith hauled him off as he decided to change back to 4-4-2 following a wretched first half.

The U's gave a much improved second-half performance and were unlucky not to earn a point.

But the 1-0 defeat was certainly not the start Smith, or the fans, were looking for.

"It's disappointing," Smith admitted afterwards. "I wanted us to start without getting beat. We had five new players and Peterborough played like a team that's been together for four or five years. The lads who have come in did OK. Jarman was a bit unlucky in that he was the one sacrificed at half-time.

"I tried to do something which I thought would work and it didn't. But if we want to advance and go up the league, we will probably need to play that way. It wasn't the system's fault. In the first half, people didn't work hard enough and create the space we needed. Powell's starting position, which was quite forward for a wingback, meant Posh had acres of room behind him and they exploited it to devastating effect.

"I could see after five minutes where our problem lay and I had to decide whether to bring Paul back.

"Yet the long diagonal ball from Jarman to Powell was the one let-out we had and Paul didn't really want to come back.

"You try things in life. But it wasn't just that, the midfield wasn'tK working.

"The second half was a lot better and we probably should have had a penalty when Steve Anthrobus was fouled in the box.

"I thought Jon Richardson was tremendous and at least after seeing that performance people won't be talking about Mark Watson any more."

He added: "We've got a long, long season ahead of us and although the fans are disappointed at the moment, I'm sure at the end of the season they'll be saying: 'maybe he was right after all!'"

New striker Manny Omoyinmi reflected: "We've got to work as a team. It's no excuse to say that it was because we had a lot of new players and Peterborough are more used to playing together.

"We need to start off in the first half as we started off in the second, and I guarantee next week we won't need that long to get going."

Peterborough manager Barry Fry said: "I was very pleased that, despite being the away side, we created more chances than the home side.

"We looked very fit, had great movement and we played football."

Meanwhile, Smith has to decide what to do with Jarman, and whether to keep him beyond the one-month contract he has signed.

He says two years ago Jarman was considered the best thing to come out of Wales since John Charles, yet last week, after the 1-1 draw in a pre-season friendly at Slough, United's manager declared: "He can play in a five but he seems to struggle in a four."

But Smith isn't giving up on the wingbacks idea. "We're not going to just abandon it. I'm sure there'll be occasions we play that way, we just need to play it better."