Nottingham Forest have completed the signing of Celtic centre-half Kelvin Wilson for £2.5m.
The 27-year-old, who left Forest for Celtic on a free transfer in the summer of 2011, has signed a three-year deal.
"It's massive club with great ambition, great players and great management - to me it was a no-brainer," Wilson told BBC East Midlands Today.
Wilson, who won two league titles with Celtic, is available for Saturday's game at Blackburn.
Forest bid £1.5m for the centre-back last month, but Celtic wanted more and were keen to keep him for the early stages of the Champions League.
It is in the English Championship that Wilson hopes to take his career forward by helping Forest challenge for promotion.
While he admits turning his back on Champions League football was tough, he insists it is the right move at the right time.
He also stressed that he had not put in a transfer request to force Celtic manager Neil Lennon to sell.
"Neil really didn't want me to go, but he respected my decision," Wilson said.
"It was hard, you are playing with international players week in and week out, Champions League football, but I'm coming to Nottingham Forest.
"I'm 27, going on 28, at the peak of my career so it had to be the right club.
"I wouldn't have just joined any club, it had to be the right club and it doesn't get more right then Nottingham Forest for me."
Meanwhile, Forest are still interested in signing Middlesbrough midfielder Grant Leadbitter and are also keen on Wolves winger Bakary Sako.
However, Forest's chances of signing Wes Morgan now seem to be over. Leicester City have rejected two bids from the Reds for their skipper and are desperate to keep him.
Forest had already signed Jack Hobbs and, having now signed Wilson, their priorities are to strengthen their attacking options.