The goalkeeper confessed his time on the field as a striker was indeed "15 minutes of fame", but any longer and he could have ended up in hospital!
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Harper: "It was good to get on up front and something I've always wanted to do.
"I played centre-forward until I was 17, not that you could tell against Celtic, but it shows the situation here.
"In pre-season, though, you have to take precautions, and when Butty hurt his knee I looked along the bench and there was nobody left to come on apart from myself and Tim Krul.
"We needed somebody to play outfield for a time and it was me who got the shout. I enjoyed it.
"We have to limit the injuries. Butty has tweaked his knee and Steven Taylor his ankle and, although they aren't anything major, you have to take precautions.
"We need strength here still. We lost seven or eight players to the squad and we have had four players come in.
"We were actually short last year and this shows the importance of getting three or four new faces in.
"I understand that the manager has been told there is money to spend although he doesn't know how much.
"I am sure he is working hard behind the scenes with his staff to get the right players in.
"Maybe this will end up being a quiz question, but I don't know what I would have done if James Milner's shot in the last minute had hit the post and come to me. It might have been different.
"Even when Steven Taylor went off and we went down to 10 men, I still enjoyed my 15 minutes out there.
"But if it had been for longer then perhaps I'd have ended up in the RVI!
"On a serious note, there were a lot of encouraging signs against Celtic - they started very well and passed the ball very well.
"They looked bright and bubbly even though they were jet-lagged. We got a goal against the run of play and then a couple more.
"It was important to step up a level after the two opening games. We have to continue it against Juventus."