Jan Vennegoor of Hesselink headed the only goal of the game in the final stages to beat the 2004 European champions, who like Celtic go straight into the group stages this season.

The win may give manager Gordon Strachan some ground for optimism that Celtic's atrocious away record in the Champions League can improve - they have taken just one point from a possible 45 in their group matches.

Strachan, who employed a 4-5-1 formation with Georgios Samaras up front on his own, admitted he had used the three-match trip to Portugal partly as an exercise to plan for improvement on the road.

Celtic had previously needed another late header from Vennegoor of Hesselink to earn a 1-1 draw with Middlesbrough, and lost 1-0 to Cardiff.

Strachan said: "Against Middlesbrough on Tuesday, our idea was to keep possession of the ball for as long as we could.

"It might have killed the game as a spectacle and I know that. But we're trying to educate ourselves in how to win things when we`re away from home in Europe."

The Celtic manager has been frustrated so far in the transfer market with only Derry winger Paddy McCourt joining the squad that finished the season as champions.

A bid for Auxerre and Romania defender Gabriel Tamas appears dead after chief executive Peter Lawwell could not strike a favourable deal.

Tamas no doubt impressed Strachan at Euro 2008, where the Celtic manager worked as a BBC pundit. But the former Coventry and Southampton manager is working on longer-term options.

"We have four or five targets at the moment - a couple in the same position - and we'll work away at getting them," he said.

"Of all the ones we are talking to right now, only one has popped up on the radar in the last couple of months.

"There have been ones you look at in the European Championships and go `I like him'. Too dear. 'I like him'. Too dear."

At least one defender is sure to be on that shortlist, especially after Celtic loaned out defender John Kennedy to Norwich, and seek to offload the highly-paid Bobo Balde.

But one player who does not appear to be on his way out is Thomas Gravesen, despite Strachan's admission that he is unlikely to play for the first team again.

The Danish midfielder was left behind while Celtic travelled to England and Portugal and played alongside transfer-seeking Derek Riordan for the reserves.

However, his agent John Sivebaek insists the highly-paid 32-year-old will not be forced out before next summer.

"Thomas has a contract and intends to see it out," Sivebaek said.

"There have been no requests from any other clubs and he is happy at Celtic.

"Of course, he would love to be playing, but that's the manager's decision. At this stage, it seems like he won't get another chance.

"The unfortunate thing is that Thomas is a very good player. It would be a real shame if he doesn't get a second opportunity."