Martin O'Neill feels selling top-scorer Mark Viduka was what helped set his Celtic side on the road to success.
While the Australian's temperament may have been questionable he had a superb goalscoring record for the Hoops, hitting 30 goals in just 37 SPL games.
His goals covered for the absence of Henrik Larsson in the 1999-2000 campaign, but Viduka was sold to Leeds for £6million shortly after O'Neill's arrival.
Losing your top goalscorer would ordinarily spell disaster, but the Irishman feels it made his team better.
O'Neill explained to Sky Sports : "Viduka leaving allowed me to buy Chris Sutton which helped immensely.
"He was a brilliant partner for Henrik Larsson so that worked out terrifically.
"Henrik was in fantastic form that particular season. Sorry, he was in fantastic form every season that we had him.
"He really loved playing with Chris Sutton.
"Sutton was a top-class player, there was no doubt about it. He had won the title in England with Blackburn Rovers.
"Going forward we became much more potent then."
Sutton would go on to score 86 goals in 199 games for Celtic, but he also helped get the very best out of Larsson.
The Swede scored 53 goals in 50 games in the 2000-01 season and topped 40 in two of the three subsequent seasons before moving to Barcelona.
