Sergio Romero kept a clean sheet, despite being tested at times by the Royals, while a first-half penalty given by the VAR system and confidently converted by Juan Mata, plus a second goal on the stroke of half-time by Romelu Lukaku, were enough for the Reds to win.
Solskjaer said, "It was a tough game, but 2-0 and a clean sheet [is good]. I made it tough for us because when you make nine changes it is never easy for a team that has never played together so I am delighted that we are in the next round. We work together every single day and of course we know we need some fitness work and some work on relationships, but today I put a team together that has never played together and we are through so that is good.
"We have performed a lot better, but you can't ask for fantasy football every time and with the changes I made you can't expect it to have the same flow and rhythm we normally would. Some individual quality at times managed to get us through. We are going to have some days to recover and then train hard because we know that if that performance is repeated at Wembley against Spurs, we are not going to come back with a clean sheet and any points."