Leyton Orient head coach Richie Wellens was left with a sense of frustration after his side's Carabao Cup exit at Plymouth Argyle.

The hosts had two early efforts ruled out for offside, before Ben Waine capitalised on a mistake by Omar Beckles to open the scoring at Home Park.

And Waine converted a cross from Freddie Issaka to put the Championship side 2-0 up at the break and leave O's with a mountain to climb.

"Both goals were bad mistakes," said Wellens. 

"The pass back is short, and we've give them a good leg-up in the game, we've allowed a winger to pull a ball back in an area.

"They were good but we were so lethargic, slow and sloppy and reactive and they've got a team that was fresh, full of energy, none of them played at the weekend, that wanted to play forward and run forward.

"Their two wingers caused us a lot of problems. We just didn't listen to information and our full-backs were too passive."

O's had gone close to opening the scoring when a Tom James corner was deflected onto the far post and Beckles thundered the rebound against the crossbar.

And Ethan Galbraith fizzed a rising shot just over inbetween Waine's two goals, while Theo Archibald sent a free-kick narrowly over in the second half.

"Second half, our full-backs step up, we're more aggressive," added Wellens.

"There's things we need to work on. There's two of our front four in Jordan Graham, who was starting his first game in three and a half months, and Joe Pigott, who is trying to get up to speed.

"First half they were very good, second half we were very good. But they hurt us. We didn't make them pay in the final third."

Galbraith went off with suspected concussion late on, while Wellens confirmed Aaron Drinan and Dan Agyei are out long-term, but Ed Turns and Max Sanders could feature soon.

"Forget injuries, we've stepped up a level, what we need to do is work harder," he said.

"People say we won the league easy last year, we didn't. There was loads of games we had to work hard to get over the line.

"We've just dropped off. That first half I wasn't happy at all. When people don't work, I'm not happy with that. But then so proud of the second half.

"It's there and you feel a little bit cheated when they go out and start lethargic.

"It's a long old way, you need to represent your club, every time you step on the training field, every time you step on the pitch.

"But let's be realistic, it's the worst draw possible for any London club, it's a long, long way down here. And you have to respect that their home record over a long period of time now."

O's return to League One action to host Portsmouth on Saturday.