"It is difficult to be pleased with the score, the way you play and everything else outside that but at least we won the game."Blues manager Marta Tejedor
Lucy Staniforth saw off stubborn Sunderland with the free-kick that decided a 1-0 win over her former club.
Windswept conditions were not conducive to flowing football and while Blues created plenty of chances, Tejedor admitted it had not been a polished performance.
"I am pleased with the fact we won the game and we went through," said Tejedor.
"It is difficult to be pleased with the score, the way you play and everything else outside that but at least we won the game.
"The wind, maybe the pitch being soft, the opponents playing so deep, it can make it tough.
"If you manage to score early then it can change things. We had chances from the very beginning but couldn't score and the more the match went on, the more anxiety and stress you get.
"All of it built to a really uncomfortable match but we got through it.
"At the end of cup games the important thing is to still be in the competition at the end.
"In the future no one will care how you got there if you can keep progressing so I am happy with that and looking forward to the next round."
Tejedor was without the services of Adrienne Jordan and Chloe Arthur for the tie but revealed both could be back in contention for Sunday's home clash with Bristol City in Women's Super League (2pm).
"They both had little problems in the Chelsea game and did not feel completely recovered so we decided not to play them," added Tejedor.
"Hopefully they will be okay for the next match."
*The quarter-final draw will be broadcast on BBC Radio 5 live on Monday (February 17) at 8.45pm with ties scheduled for the weekend of Sunday, March 15.
Tickets for the Bristol City match can be purchased HERE.