Julio Cesar's headed goal in the 19th minute had raised Olympiakos' hopes of recording their first ever away win in Europe's premier club competition at their 30th attempt and vastly improving their own chances of advancing,

But Totti's clinical finish denied the battling Greeks, the Italian World Cup winner redeeming himself after his 32nd minute spot-kick had been brilliantly saved by Antonios Nikopolidis.

A draw left Roma second in group D on seven points, five ahead of both Olympiakos and Shakhtar Donetsk, with two games left to play. Valencia booked their place in the knockout stages after drawing 2-2 against Shakhtar, a result which left them top on 10 points.

Tension had been raised prior to the match following attacks on visiting fans by Roma supporters the previous night, but there was no trouble inside the Olympic stadium.

Roma coach Luciano Spalletti criticised his team for making life hard for themselves.

"We need to start putting away our chances if we have ambitions of going far in this competition," he said.

"The opportunities are being created, but we have to put them away. If you fail to do so in this competition, with all the quality teams that you come up against, you will inevitably be punished sooner or later."

Olympiakos' Norwegian coach Trond Sollied admitted his team's chances of surviving the first round cull were slim.

"The damage was not done here, but in Athens," he said. "We should have taken at least a point from that match and we ended up with nothing.

"Tonight we played well, but we have a habit of conceding silly goals and it cost us again."

Roma started with Totti employed as a lone striker supported by a five-man midfield.

Simone Perrotta, who scored Roma's winner in Greece a fortnight ago, only made the substitutes' bench as he was still feeling pain from a knee injury.

Olympiakos were without Alberto Castillo after the influential Uruguayan striker complained of breathing difficulties.

Olympiakos gave Roma a fright in the sixth minute when former Brazilian superstar Rivaldo, who used to play in Italy for AC Milan, fired an angled shot which Alexander Doni did well to parry.

Roma failed to heed the early warning and they soon fell behind.

Rivaldo delivered a right-wing corner to the edge of the six-yard box, and Julio Cesar outjumped his marker to plant a firm header past Doni.

Roma saw their appeals for a penalty turned down in the 23rd minute when Max Tonetto's left-footed drive appeared to be handled by Michal Zewlakow.

Totti's deflected free-kick was unconvincingly palmed away by Nikopolidis as Roma raised the tempo, before Julio Cesar scythed down Rodrigo Taddei in the box with a poorly-timed lunge.

Totti struck the spot-kick with plenty of venom, but Nikopolidis guessed correctly, diving to his right to pull off a stupendous save.

Perrotta came on for Matteo Ferrari for the start of the second half to add more thrust to Roma's midfield, but even his introduction failed to lift the 2001 Italian champions.

Roma needed a creative spark and Totti finally provided it midway through the second half.

A sublime touch from the Roma captain brought Taddei's lobbed pass under control, and his angled shot swept past a helpless Nikopolidis.

Roma substitute Mirko Vucinic might have nicked all three points for Roma, but his two late efforts were saved by the excellent Nikopolidis.