Keane, the 31-year-old former Ireland captain who underwent serious hip surgery last season, is expected to lead United out for their first pre-season friendly of the year, against Scottish giants Celtic at Seattle's Seahawks Stadium on Tuesday.

He took longer than expected to shrug off the effects of the operation and, before United went on to lift their eighth premier league title in 11 years, there were fears that constant wear and tear was beginning to catch up with him.

But Ferguson told reporters: "Roy has been fantastic.

"The summer he's had, and the pre-season, has been excellent. It will all (help) bring him back."

Ferguson insisted his captain had recovered well from surgery, comparing Keane's efforts favourably with those of Robbie Fowler and Fredrik Ljungberg, who underwent similar operations.

"Roy is giving away years (in age) to Fowler and Ljungberg," Ferguson said from United's training base in Portland, at the start of their four-game pre-season tour of the United States.

"We know now what a serious operation it is, one not to trifle with."

However, with Keane's longevity still open question, Ferguson has chosen to bolster his midfield.

New signings Eric Djemba-Djemba and David Bellion are likely to be joined at Old Trafford by Brazilian Kleberson once the U.S. tour is over.

French winger Bellion could make his United debut on Tuesday.

Keane was a boyhood Celtic supporter and there have been suggestions in the past that he could finish his career at Parkhead.

With a sell-out 67,000 crowd at Seahawks Stadium on Tuesday and Celtic already well into their pre-season programme, the game is likely to provide him and his United team mates with an instant wake-up call.

Their pre-season friendly two years ago at Old Trafford -- won 4-3 by Celtic -- was competitive to the point of nastiness, and Ferguson said: "Celtic don't play friendlies.

"It's a great testimony to their club...they play to win."