Liam Rosenior defended his decision to rotate much of his Chelsea team in their dramatic extra-time victory over Championship side Wrexham in the FA Cup. 

Chelsea emerged 4-2 victors at SToK Cae Ras on Saturday but were pushed the distance by their opponents, who saw George Dobson sent off in the 93rd minute. 

Sam Smith's 18th-minute opener was cancelled out by an unfortunate Arthur Okonkwo own goal, but Wrexham retook the lead through Callum Doyle with 12 minutes left. 

However, Josh Acheampong levelled things up four minutes later, before extra-time goals from Alejandro Garnacho and Joao Pedro sealed their spot in the last eight. 

Indeed, Chelsea have now won their last 19 FA Cup games against sides from a lower division, scoring 62 goals and netting 2+ goals in 18 of those matches.

But they were made to work for their win, with Rosenior's squad selection challenged after he made nine alterations to the side that beat Aston Villa 4-1 in midweek. 

Cole Palmer, Moises Caicedo and Enzo Fernandez were not in the squad, while Marc Cucurella and Joao Pedro came off the bench, though Rosenior insisted the upcoming fixture list forced his hand to ensure his players remained fresh. 

Rosenior said: "We are going into a period of games where, for example, Romeo Lavia can be really important because he has to play minutes.

"We have to get him up to speed. Dario Essugo, we have to give him time on the pitch.

"[Lavia] is a top player, but you can't expect perfection from a player who's been out for four months.

"It's not just about your first 11 or your first 12 players to get us to where we want to be.

"The only way our players and our squad are going to help us achieve what I think is possible is for them to be sharp and ready.

"The amount of games my squad have had in the last 18 months is the biggest in the world. So at some point I have to trust the group.

"They repaid my trust with the result tonight."

For Wrexham boss Phil Parkinson, meanwhile, he was left to rue the decisions made by VAR, with two interventions from the technology going against his side. 

Dobson was initially awarded a yellow card for a high challenge on Garnacho before a VAR review upgraded it to a red, before substitute Lewis Brunt had a goal chalked off for a marginal offside with the game at 3-2 in extra time. 

"Without VAR we don't get a player sent off and that goal certainly stands, so it's against us tonight," said Parkinson. 

"It's my first taste of it and I know the rule is that is has to be a clear and obvious mistake for the decision to be changed – and I think the referee's got to back his judgement of the real time, instant moment. He was in a great position to see it."