Celtic look highly unlikely to progress in the Europa League after they endured a frustrating goalless draw in Hamburg, which leaves them bottom of the table.
Barry Robson blasted an early effort over the bar from 16 yards and twice striker Scott McDonald was denied by Hamburg's alert goalkeeper Frank Rost.
Lukasz Zaluska saved well from Marcus Berg and surpassed that when he tipped a David Rozehnal header over the bar.
Celtic must win their final two games and hope Hamburg lose theirs.
With less than 90 seconds on the clock Berg fired a shot at Zaluska but Artur Boruc's replacement did well to block with his feet.
Incredibly, this was Celtic's second scare of the match, Gary Caldwell blocking acrobatically a Jonathan Pitroipa volley from six yards in the first minute.
With Celtic desperately needing a win, they drew breath and hit back instantly down the left, the ball falling kindly for Robson who whacked a left-foot shot over the bar from 16 yards as the German defence rushed at him.
A bursting run from Samaras had the Hamburg defence retreating as the match continued apace.
The Greek's pass to McDonald was perfectly weighted and from inside the box the Australian fired a low shot too close to Hamburg's goalkeeper Rost, who got down well to save.
As the game swung to the other end of the pitch Caldwell picked up a yellow card when a delicious flick by Jose Ze Roberto wrong-footed the Celtic captain for the night.
Thankfully for Celtic, the Brazilian swept his free-kick wide.
Marcell Jansen's low shot in the 20th minute was parried by Zaluska and slack passing by Celtic in central areas threatened to undo their Europa League chances as first Pitroipa and then Jansen again kept Tony Mowbray's side pinned back.
McDonald, dropped by Australian coach Pim Verbeek for their match against Oman, was presented with another chance when a clever Aiden McGeady pass from the touchline saw him racing in from the left-hand side of the box.
Like his first opportunity, McDonald's shot had power but was directed straight at Rost.
In a scrappy beginning to the second half, Hamburg came close to taking the lead when Joris Mathijsen leapt to meet a free-kick and the ball bounced off his back and on to the top of Zaluska's crossbar.
Landry N'Guemo had the 2,500 Celtic fans peering through their fingers in terror when his crossfield pass was cut out by the electric Eljero Elia, who sped forward and cracked a shot at goal.
Zaluska parried into the path of Pitroipa, who was prevented from shooting from close range by a fabulous intervention by Caldwell.
As the hour mark approached and with Hamburg pressing Celtic deep into their own half, Mowbray sent on Marc-Antoine Fortune and Lee Naylor, McGeady and McDonald making way.
It was a brave move by Celtic, Naylor taking over Danny Fox's left-back role as his team-mate moved into the left side of midfield vacated by McGeady.
N'Guemo set Samaras racing through on goal with a delightful ball over the top of the Hamburg defence, but with only Rost to beat the Greek shot feebly and the game remained goalless.
With Hapoel Tel-Aviv leading Rapid Vienna, a goal for Celtic was essential as stalemate at Hamburg's Nordbank Arena would leave the Germans needing just one more point to make it impossible for the Scots to progress.
Yet the Bundesliga side continued to apply the pressure and, when Rozehnal escaped Glenn Loovens at a Ze Roberto free-kick, only a superb save by the impressive Zaluska prevented the Hamburg defender heading the opener.
Celtic made a late surge as Hamburg appeared to tire, with final substitute Niall McGinn offering the visitors fresh legs in midfield.
But as the match reached its finale, there was a feeling that the missed chances by Robson and McDonald would haunt the Scots.
The final whistle not only ended the 90 minutes but most likely Celtic's chances of advancing from Group C.
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