The Scottish striker joined Sunderland from relegated Wolves and eyebrows were raised when O'Neill elected to splash out a significant figure to secure his signature.

But after scoring three times in his first two games, including Saturday's opening goal in their 1-1 draw against Liverpool, O'Neill believes his decision to bring in the forward is proving a good call.

"So far, he has been absolutely terrific, I am just delighted with him," he told reporters. "I just couldn't be more pleased.

"All sorts of figures seem to be bandied around - I heard we paid £14 million for him - it was £12 million, but he seems to be worth every single penny of it.

"I am just pleased for him. It's nice for the crowd to take to him at this minute - that will give him a boost of confidence as much as anything else, but goals, of course, are very pleasing."

Fletcher was brought to the Premier League by then-Burnley manager Owen Coyle in 2009 and he notched eight goals in the club's unsuccessful bid to stay in the top flight.

He then moved on to Wolves for a fee reported to be around £3 million and after two seasons at Molineux earned a move to Sunderland in August.

Despite being one of the Premier League's most expensive strikers, however, Fletcher is in international exile after a bust-up with Scotland manager Craig Levein.

But when asked by a follower on social networking site Twitter whether he would return to the national team if asked by Levein, he replied 'yes'.