United manager Simon Grayson said he had plenty of food for thought after Tuesday's FA Cup second round win against Kettering - but admitted it was mission accomplished as his side booked a third round date with Manchester United.

Four goals in 11 minutes in extra time secured United a place in the third round after Kettering had earlier cancelled out a Luciano Becchio goal to take the tie into extra time.

"The 5-1 scoreine reflected the chances we had," said Grayson. 

"We had enough chances to win three matches. We got the ball in good areas, we hit the post and the woodwork and had some blocked, but at 1-0 you can still concede and we weren't good enough in the second half.

"You set high standards and we didn't reach those standards. Credit to Kettering because they caused us a few problems in the second half, but we dug in there and got a result whuich we deserved. But it certainly wasn't comfortable.

"We're through and that's the main thing. We had 20-odd attempts in the first half and only hit target five times which shows we needed a bit more composure.

"I'm delighted with the goals we've scored, but there's a lot to work on.

"We want to make sure we are better as a unit and as individuals and I'll keep challenging the players to do that."

"It was another Grayson substitution that eventually settled the tie, Mike Grella stepping off the bench to score two stunning goals in the final period of extra time.

"He's a clinical finisher," said Grayson. "We know that. We had to try and win the game and he showed us what he showed in training.

"I'm delighted that he got the goals and we're through.