MIDDLESBROUGH footballer Abel Xavier faces both the sack from his club and a lengthy worldwide ban from the game after failing a drugs test.

The 32-year-old full-back, who joined Boro on a one-year deal at the start of the season, was selected for a random test at the end of last month's Uefa Cup first-round second-leg game with Greek side Xanthi.

Boro's place in that competition is now at risk following the Portugal international's failed test.

His first urine sample has returned a positive result and Fifa has banned him from all competitions while Uefa conducts a disciplinary investigation.

Uefa officials will meet on Monday morning to discuss the situation, with the governing body expected to sanction further tests on a second sample of Xavier's urine.

At this stage, neither Fifa nor Middlesbrough are revealing what drug has shown up in the defender's system, but it is understood that it is a non-recreational substance.

Xavier will release a Press statement this morning in which he will protest his innocence and outline his determination to fight any ban.

The former Everton and Liverpool defender is known to have been suffering from a virus recently and is expected to claim that he was taking special supplements imported from the US.

These supplements could have contributed to a positive test and are likely to be at the heart of his defence.

Uefa's drug laws state that a player may be granted a therapeutic use exemption but, an application must be made in advance of any test.

Middlesbrough officials, who are understood to have known nothing about the supplements imported from the US, are refusing to make any statement at the moment.

But, Xavier was pulled from the squad that drew 1-1 with Portsmouth at the weekend and was not expected to travel to Zurich for Thursday's Uefa Cup group-stage game with Grasshoppers.

Xanthi are expected to appeal against the result of last month's second-leg game, claiming that, by testing positive, Xavier has rendered the match invalid.

But, in 2002, the Court of Arbitration for Sport ruled that Russia should not be punished after their player, Egor Titov, failed a drugs test in similar circumstances.

Fans were shocked by the news of Xavier's failed test, which was confirmed at about 5.30pm last night.

Sue Bargewell, spokeswoman for Middlesbrough's Official Supporters Club, said: "We're all still reeling from the news at the moment - it's still too much to take in.

"The ironic thing is that Abel Xavier was the guest of honour at our meeting last week and he was brilliant.

"He was probably the best guest we've ever had, but obviously this news taints everything that happened. We've got to wait to see exactly what he's being accused of but, at the moment, the over-riding feeling is that he's been a very silly boy.

"It's bad enough that the club's name is going to be dragged through the mud while all of this goes on. But the worst thing of all is that we could be kicked out of the Uefa Cup."

Xavier, who was banned from international football for six months for man-handling a linesman following the semi-final of Euro 2000, is the first Premiership player to test positive for a non-recreational drug. Former Chelsea players Adrian Mutu and Mark Bosnich were both banned after testing positive for cocaine.

Manchester United defender Rio Ferdinand was banned for eight months when he failed to turn up for a random test in September 2003.

Teesside anti-drugs campaigner Tina Williams, of PANIC (Parent and Addicts against Narcotics In the Community), said: "It really isn't setting a good example to the children in the area."