Long faces his old club today.
"I have to be honest and say it was a deal I never saw coming," said Bruce.
"It wasn't until 48 hours before the move we heard about Southampton's interest and then it was done very quickly.
"Sometimes you get an offer for a player that you just can't refuse. Longy was one of those.
"We doubled our money in a short period of time and it enabled us to strengthen in other areas.
"We were able to go out and get players like (Mohamed) Diame and (Abel) Hernandez.
"Sometimes, as a manager, you have to make a decision and this was one that came out of the blue really."
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