Dexter Blackstock returns to St Mary's tomorrow with George Burley admitting: "I couldn't hold back his career".
The Saints boss was unable to give the 20-year-old striker the summer assurance he wanted regarding first team football.
So, when QPR came in with an offer of £500,000 that includes a good sell-on clause, Burley agreed to let Blackstock move - for the sake of his career.
Burley said: "Dexter was a great kid and he was at a stage in his career where he needed to play regularly. I spoke to him and said I couldn't offer him that guarantee here.
"The club got a fair price and everybody appreciates what Dexter did for the club. He's certainly a lad with a big future in the game."
Blackstock, whose goals gave Burley has first win as Saints boss against Brighton in January, has already enjoyed mixed times at QPR.
The manager who bought him, Gary Waddock, was last week replaced by John Gregory.
But Blackstock grabbed his second goal in six starts to seal a 2-0 home win against Hull in Gregory's first game in charge last Satirday.
Blackstock scored eight goals for Saints in 19 starts - 35 appearances in total - after moving to the club from Oxford United in 2003.
He announced his arrival on the big stage with a League Cup hat-trick against Colchester at St Mary's in October 2004 - the first triple ever by a Saints sub.
Burley added: "Dexter went on loan last season at Derby and had pre-season here.
"But we had four experienced strikers so there wasn't a guarantee. He wanted regular first team football and we got a fair price for him.
"If he would have stayed here, his career might have been on hold.
"That happens with young players.
"Dexter is 20 now and youngsters come to a point where they want to play first team football.
"And as a manager you have to make a decision to either hold them back or, if you get a realistic offer which helps you strengthen the squad in other departments, these things have to be done.
"Dexter has a good all-round game.
"He's a goalscorer, very dangerous in the box and good in the air and that's where his strengths lie."
Blackstock will be aiming to become the third ex-Saint to score on his first St Mary's return in recent years.
Kevin Davies, who joined Bolton in 2003, grabbed the winner at Saints in April 2004 while James Beattie netted for Everton in February 2005 a month after leaving the south coast.
For more Saints v QPR previews, don't miss today's Daily Echo.
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