Ben Pollock, Sean Longstaff, Lewis McNall and Dave Watson

By Dan King - Newcastle United Digital Editor

Dave Watson has warned his Newcastle United youngsters that they must be "mentally right" if they are to avoid falling victim to an FA Youth Cup upset this week.

The Magpies entertain AFC Wimbledon in the fourth round of the competition at St. James' Park on Wednesday (kick-off 7pm), having reached the quarter-final stage for the past two seasons.

And the Dons have already caused one shock after beating Watford on penalties at Vicarage Road in the third round.

"I wasn't totally surprised because strange things do happen in the cup," United's under-18s coach Watson told

"We've seen the game and they equalised in the last minute, took it to penalties and went through that way.

"That's what great about this cup - it doesn't matter what division you're in, what big names you've got; it's all about doing the job properly and winning the game on the night."

Many of Watson's players will run out at St. James' Park for the first time on Wednesday.

However midfielder Sean Longstaff was a big part of last season's run to the last eight, where Newcastle lost to eventual winners Chelsea, and Watson said: "Sean has had good experience on that pitch.

"Lewis McNall and Owen Gallacher have played for the under-21s and Mackenzie Heaney has been involved there in youth games.

"So we've got a good bit of experience - but if you don't perform on the night, you don't get anything so we've got to be mentally right and the rest should hopefully take care of itself."

United saw off non-league Ilkeston in the last round and were 3-0 up at half time before the home side threatened to stage a dramatic comeback.

"We made hard work of it," admitted former Everton and England defender Watson.

"The kids did great to get into a 3-0 lead and then something they've learnt from the game is that you come out in the second half and you aim to win the second half, whereas I think one or two heads thought the game was over and it was just a matter of playing the game out.

"They got back to 3-2 and they possibly could have equalised and taken it to extra time and penalties, so lessons were learnt - hopefully."

Admission on Wednesday night is £3 for adults and £1 concessions.