Sir Alex Ferguson has accepted Louis Saha's long-running injury problems as part and parcel of signing a player "built for speed".

Saha's cup final injury curse has struck again after the Frenchman was ruled out of Saturday's FA Cup showdown with Chelsea at Wembley.

It is the fourth time Saha has missed out on a final appearance in the competition, merely adding to the misery of the suspension which ruled the former Fulham man out of last summer's World Cup Final defeat to Italy.

Having barely played a game since the New Year, and with Ferguson hinting many of Saha's problems are mental rather than physical given his refusal to play unless he is 100% fit, there has been mounting speculation the £12.8million man could be heading for the Old Trafford exit door this summer.

However, Ferguson could not have been more enthusiastic in his praise for the 28-year-old, who scored 13 goals this season but only one - against Reading - since the first week of December.

"Louis is the type of player who is built for speed," said Ferguson.

"Over the years he has always had hamstring problems but we were aware of that when we signed him.

"He is such a fantastic striker, we decided to take the risk and in some ways we are pleased with that.

"He has made a good contribution when he has been available and we just accept it as part of the game."

Saha's latest problem was a knee injury picked up during the second leg of the Champions League semi-final with AC Milan.

Ferguson revealed the forward has had a scan to determine the extent of the problem, with United to determine their next course of action over the coming days.

"We know what the problem is, now it is a matter of deciding what to do next," said the United boss.

"It doesn't necessarily mean he will have an operation but it is something we are considering.

"You can't apportion blame for the injuries. It just happens sometimes.

"He started off with a hamstring injury, over-compensated when he came back and injured his knee."

Whether Saha stays or not, it seems certain Ferguson will bring in at least one new forward during the summer, with Dimitar Berbatov, Michael Owen, Fernando Torres and Klaas Jan Huntelaar all linked with the Old Trafford outfit.

"We are fortunate things fell into place for us a little bit," said Ferguson.

"Louis scored 13 goals at an important part of the season. Then we were fortunate to get Henrik Larsson in to continue that penetration up front.

"And come the last part of the season, Alan Smith came in and did a fantastic job."

Meanwhile, Ferguson says he knew record-breaker Ryan Giggs was 'a certainty' to make it when he first saw him as a 13-year-old.

On Sunday, Giggs eclipsed Alan Hansen and Phil Neal by collecting a ninth championship medal, one more than the illustrious former Liverpool duo.

Now, handed the captaincy in the absence of injured Gary Neville, Giggs will lead Manchester United out against against Chelsea at Wembley on Saturday in the FA Cup final, knowing he is one win away from becoming the most decorated player in that competition as well.

A winner on four previous occasions, the Cardiff-born star can become only the fourth player to celebrate five times.

And given the other three - Arthur Kinnaird (The Wanderers and Old Etonians), Charles Wollaston (The Wanderers) and Jimmy Forrest (Blackburn) - completed the feat at the back end of the 19th century, Ferguson recognises Giggs' achievement as astounding.

"If Ryan stopped playing tomorrow, he would still stand very high on the all-time list of Manchester United greats," said Ferguson.

"To win nine Premiership titles is amazing and to get five FA Cups would be wonderful too.

"He has spent 16 years tramping up and down the wing, there is no player who has done that in the history of the Premier League."

In his autobiography 'Managing My Life', Ferguson referred to the day he first saw Giggs in action, likening the winger to 'a dog, chasing a piece of silver paper on the wind'.

Nothing much has changed in the intervening years.

Giggs may not have quite the same speed as old but any relative lack of pace is made up for in experience.

And, while no-one could have envisaged just what an enormous medal haul he would eventually collect, Ferguson never had any doubt Giggs would be a star.

"Ryan is the only player in my life I watched as a 13-year-old and felt he was an absolute certainty to make it," he said.

"I told Bobby Charlton he had to come down and see this kid play. All our opinions of him from that day have proved to be correct."

Quiet and composed in front of the media, Giggs is said to have a wicked sense of humour in the dressing room.

Still, he could never be viewed as brash or loud, or a demonstrative leader like his opposite number on Saturday, John Terry.

As a role model though, Giggs is perfect. Steering clear of publicity for most of his career, dedicating himself to a profession he has proved to be the ultimate in terms of success.

"People like Wayne Rooney and Cristiano Ronaldo are influenced by what he has achieved," said Ferguson.

"There is no doubt, in a quiet way, he will give advice to all the players."

With Louis Saha joining Neville on the sidelines, Ferguson confirmed his team selection will come from a group of 14 players.

His major selection issues appear to centre around Neville's right-back role, where Wes Brown is favoured to edge out John O'Shea, left-back, which could be tight between Patrice Evra and Gabriel Heinze, the only member of United's squad who did not play a full part in training today.

In addition, Ferguson's tactics will determine whether Alan Smith starts at the head of United's attack or Darren Fletcher is brought in to bolster the Red Devils midfield options.

"It is difficult because so many players have performed well for us this season," explained the Scot.

"We were left with 14 or 15 players to carry us through from the middle of March to the beginning of May.

"There were periods when we were asking Gabriel Heinze to play left-back and centre-half, Wes Brown at right-back and centre-back and John O'Shea all over the place.

"Without question, they are the lads who have won the league."

Although not an emotional person by nature, Ferguson recognises the special attraction of Wembley and is delighted he now gets the chance to walk alongside Jose Mourinho as the first managers to lead their teams out at the magnificent new stadium.

"I am so pleased we are one of the teams at the new Wembley," he said.

"When we got beaten by Liverpool last season, I was hoping the stadium would not be finished because I really wanted us to be one of the teams to take part."