LEON Best labelled his two-year spell at Blackburn Rovers as the ‘most frustrating’ time of his career after joining Championship rivals Derby on a season-long loan.

Rovers transfer listed the £3m striker in May after he made just 16 appearances for the club following his big money move from Newcastle in July 2012.

Best landed himself in trouble with comments he made on a social networking site.

But the 27-year-old puts the root of his problems at Ewood Park down to the serious knee injury he sustained shortly after his arrival.

Best said: “It has been the most frustrating time I have had in my career.

“It was the worst possible start for me at Blackburn.

“The first pre-season game, I had just scored a lovely goal and then got injured – the worst injury I have had in my career.

“It was so hard, your whole world comes crashing down.

“For my career at Blackburn, it wasn’t a good thing. But for me as a man and a footballer it opened my eyes.”

Best regained full fitness and he opened his account for the club on the opening day of last season when he struck a late equaliser against his new club Derby.

The Republic of Ireland was then dropped following comments he made on Instagram.

He subsequently apologised and he capped his return to the squad with his second goal for Rovers in a win at Bournemouth.

But he lost in place in Gary Bowyer’s starting line-up and he was the subject of a fresh club investigation following further comments he made on Instagram before he joined Sheffield Wednesday on loan in February.

Best scored five goals in 16 games for the Owls and he believes it paved the way for his move to last season’s losing play-off finalists Derby.

He said: “My aim was to go there last season, get a bit of fitness, try to score some goals and set myself up for a better move and it has worked in my favour.

“I have come to a club with massive ambition. Derby know where they want to be.”

Best will be ineligible to play for the Rams in their Championship encounters with Rovers on September 17 and January 24.

He has been given permission to feature for Steve McClaren’s side in the Capital One Cup and FA Cup.

But would not be allowed to play against Rovers in either competition.

Best has two years left on his Rovers contract, which is believed to be worth £32,000 a week.

Sources in Derby suggest it is highly unlikely the Rams are paying 50 per cent of his wages.

But Derby are paying a higher percentage than Sheffield Wednesday, who were understood to be contributing £6,000 a week.