GRAEME Souness last night urged Dutch enigma Patrick Kluivert to reveal his "true self" as his Newcastle side prepare to put their continental credentials on the line in Greece.

The Magpies trained in Athens yesterday ahead of tomorrow night's UEFA Cup last 16 clash with Olympiacos and, after finally shaking off a troublesome muscle injury, Kluivert is expected to make his first start for almost a month in the imposing Georgios Karaiskakis Stadium.

The 28-year-old was expected to spearhead Newcastle's European campaign when he made his much-trumpeted move from Spanish giants Barcelona in the summer.

But, after scoring four goals in two games against Israeli part-timers Hapoel Bnei Sakhnin, Kluivert has since failed to find the net in the continental campaign.

His domestic form has not been that much more impressive, with four Premiership goals failing to mask the under-achievement of a player reported to be earning more than £67,000 a week.

With Kluivert's future remaining uncertain - there is no hint that his one-year deal will be extended in the summer - the next two months will be crucial in determining where the former European Cup winner goes next.

And, after admitting that Olympiacos will provide his side's toughest test yet on the continental stage, Souness has challenged Kluivert to score the goals that could take United a massive step closer to their first major trophy in 36 years.

"He has a real chance now," said the Newcastle boss, who can still boast a 100 per cent record on European soil this season.

"We are looking for goals from him and for him to put a run of games together and kick us on.

"His time with us has been stop-start, stop-start. He needs goals now, he needs to play half-a-dozen matches back to back then play every game after that. That's when we will see the true Patrick Kluivert. He hasn't done that for us.

"He needs to be a consistent performer. He's a striker and he will be judged on how many games he plays and how many goals he scores, the same as all strikers."

Kluivert is not the only player with a point to prove tomorrow night, as centre-half Andy O'Brien will also attempt to muscle his way back into Souness' plans.

The Republic of Ireland international has been squeezed out of the first team picture, despite signing a three-year contract extension last month.

With Jean-Alain Boumsong increasingly starting to look like an £8m man, and Titus Bramble finally finding the consistency that Souness feels his game is lacking, O'Brien has only started two Premiership games since the Boxing Day draw at Blackburn.

It is a different story in Europe though as, with Boumsong being cup-tied, O'Brien has played a prominent role.

The Irishman will feature again tomorrow and, while Souness remains delighted with his first-choice pairing's recent displays, he maintains that his selection policy is not set in stone.

"Andy's been fantastic," he said. "He's one of those players who is having to wait. Both Titus and Jean-Alain have been excellent, so he's going to have to wait his turn. This is a chance for Andy to make life difficult for me."

Nicky Butt and Jermaine Jenas have also been playing a waiting game recently, with Souness preferring Lee Bowyer and Amdy Faye at the heart of midfield.

Faye was not as his best as Newcastle squeezed past Liverpool on Sunday and, with Laurent Robert's place in the side looking far from assured as United try to keep things tight, changes could be on the cards tomorrow.

"The one area we're particularly strong in is the centre of midfield," said Souness. "Nicky's been out for a long period of time and he's still coming back.

"When you're winning, the players who find themselves not in the team have to be patient. We've tried to share the workload.