Leyton Orient head coach Richie Wellens admitted complacency had set in with his side, following their 4-2 home loss to Northampton Town.

Mitch Pinnock, Jon Guthrie and Josh Eppiah put the visitors 3-0 up in 37 minutes, before Theo Archibald replied.

And O's conceded a fourth to Eppiah before the break, with substitute Jordan Brown's second-half reply a mere consolation.

"For me, it highlights when you pick the majority of the same players week in, week out, complacency sets in," Wellens told the club website.

"We were complacent and when you get complacent, people come down 10 per cent.

"We deserved to be booed off at half-time. First 15 minutes I thought we were decent, we were at it, but some of the goals we gave away, attitude, we got what we deserved."

Four points above the League Two relegation zone in early March, O's have climbed the table under Wellens to 13th place, having taken 20 points from 11 matches.

But Wellens admitted the promotion-chasing Cobblers deserved their win, which lifted them into third place, adding: "The players have put so much into the last five or six weeks and you always get to the end of that.

"For the first 15 minutes I thought it was a competitive game. They were at it from the start, because they're going for the automatic [promotion]. Their crowd was good.

"I thought it was quite even, we could've scored a couple, they could've scored a couple, and then for the next half an hour we're playing with our flip-flops on. They're on holiday.

"We have to blame ourselves today. The first half, the majority of us were on holiday.

"Second half we played with a tempo, match them up. Jordan Brown, Harry Smith came on and did great.

"At 4-2, we had two or three chances, one or two cleared off the line. If we get that goal we can come back, but when you start like that it's difficult."

Hopes of clawing their way back late on were hit when O's were reduced to 10 men, as young defender Shadrach Ogie was sent off following a clash with Danny Rose.

And Wellens felt the day as a whole was an important lesson for his players.

He said: "I don't think Shad touched him. I think Rose has made a meal of it. But if you lean your head into someone you always run the risk.

"I think our supporters let the referee know what they felt of his performance when he was walking off, but you can't give him the opportunity by leaning your head in.

"Our momentum went, everything we were building up drifted away from us.

"It's a wake-up call, it's what we needed. We need to make sure when we finished out last game here, against Tranmere, we leave with a mindset that when we're on it we're very good, but we can never drop from that.

"Supporters pay their money to come here, they want to win and be entertained. But from where we've come from and the amount of effort, there was always going to be a dip.

"It's a lesson to be learnt, that our start can't impact the rest of the game."