United levelled before half-time and a second half penalty and a late strike gave the scoreline a gloss that the balance of play did not really warrant.
"It was a good performance really as not many teams come here and attack in the way we did, especially in the first half where we created a couple of good chances," reasoned the midfielder. "If they had gone in it would have made it a different game.
"Two of the three goals they scored were very unlike United, straight down the middle and unfortunately for us it caused us a problem. We've defended so well and to concede two goals like that is disappointing for us as a team."
JJ himself had chances to score either side of half-time when he sprinted clear of the United defences.
"The first one was a matter of hitting the target," he explained. "I knew Berba was there but I thought if I hit it hard and low the keeper might parry it and he would have a tap-in. He made a good save though and tipped it round the corner.
"The second one just wouldn't settle down for me and kept bouncing. I tried to slot it in the corner, but it happens sometimes. I am happy that I am getting myself in these positions at the moment, especially against teams like United as it can only be promising for the coming games."
JJ insists is a now a case of producing the teams's improved cup form when it comes to league matters, with Everton next at Goodison Park on Wednesday night.
"Definitely, the games keep coming thick and fast and we will be travelling again this week up to Everton, which is not an easy place to go. We're looking forward to it, everyone is in decent form and it is now a case of transferring cup form into our league games."
Jermaine Jenas believes the team were unlucky to depart Old Trafford on the wrong end of a 3-1 scoreline.We made an FA Cup exit at the 4th round stage after taking the lead against Manchester United after a move initiated by Michael Dawson, Aaron Lennon providing the supply line and Robbie Keane executing the finish.