Leyton Orient head coach Richie Wellens struggled to hide his disappointment after their FA Cup exit at National League leaders Chesterfield.

Idris El Mizouni's own goal proved the difference in the second-round tie, as the Spireites booked a trip to Watford in the new year.

And Wellens said he was gutted for the club's travelling fans and owners.

"I thought first half we was a disgrace," he told the club website.

"First six or seven minutes we was ok, in control of the game, but then they ran a bit harder, fought a bit harder and we didn't react.

"I spoke to the players at half-time and said try and put this into perspective - it's a freezing cold weekend and our supporters have saved up, worked overtime, in the current crisis when it's coming up to Christmas and the energy bills are what they are, and that first-half performance is not acceptable. Nowhere near.

"We had a warning because they beat Portsmouth here in the first round.

"More than anything I'm gutted for our supporters, for the owners, we wanted a cup run this year."

Brandon Cooper came into the side at late notice when Dan Happe picked up an injury during the warm-up, but El Mizouni headed a cross from Ollie Banks over the head of Sol Brynn and into his own net five minutes before the break.

Ruel Sotiriou was replaced by Dan Ageyi moments later and Wellens feels things are transpiring against his side.

"Little things are going against us, like Dan Happe pulling out in the warm-up, it's not ideal, because Dan is a big player for us, physically," he added.

"Sully having to go off really early in the game. Because our squad has been tested, we've been flagging people, in terms of Ruel playing 90 minutes, El Mizouni playing 90 minutes, [Jordan] Brown playing 90 minutes, and we're a little bit fatigued at the moment.

"Sully has been carrying an injury since probably the Wigan game now, probably two weeks. We're having to ask a little bit too much of Dan Agyei too early, because he's not ready yet. 

"We've got a few issues with people not quite fit. Jordan Graham has been a huge loss for us. 

"We need to work, we need to get better, but we need some quality in January. And we need some experience as well."

O's return to League One action as Derby County visit Brisbane Road next weekend and Wellens wants to see a better all-round performance.

"I think what summed the game up was we concede from an own goal," he said.

"We had a few occasions where we can slide people in one-v-one, didn't play the pass right. Our set-plays, too loopy, really poor. I'm not happy at all.

"I'm not bothered about who we play. I want to see a team that mirrors what we practice and what we work on on the training pitch. We're not getting that at the moment.

"We knew in the summer it was going to be a more testing season than last year, and our average age today was 22. That's really young. 

"I know we're coming to a non-league team but you look at a lot of their players, some of them have got Championship experience - [Tom] Naylor, [Will] Grigg.

"I knew it was going to be a difficult game, but we work on one thing, we have to change, because personnel has been changed late, and we need to get back on the bike, put a performance in against Derby.

"Bristol was ok, Wigan was decent. It's at home against a huge club so we'll rest up and it's back at it."