With Doncaster having come into the contest in excellent form, sitting fourth in the third tier, Irvine knew his team would have to be focused on the job, so he was delighted with the attitude they displayed.
Following Pablo Fornals' goal, Andriy Yarmolenko made it 2-0, an Andy Butler own goal handed the hosts a third and then Dapo Afolayan's debut strike added a late fourth to round off a positive day in east London.
"It was a professional performance right from the start," Irvine said. "It was obviously a great start for us, but right through to the end we were still trying to do the right things, make the right choices and trying to score some more goals. It was a really pleasing performance.
"We did make some changes, and clearly we did that because of the number of games coming up, but it was a team of Premier League players we had out there.
"And it needed to be because we know that Doncaster have been playing extremely well and had won seven out of their last eight games.
"I watched three of their games getting ready for this one and they were excellent in all three games, including at Blackburn Rovers in the previous round."