Great Britain were denied a win on their return from a 52-year hiatus from Olympic football as Senegal struck late to frustrate the hosts.
It looked as though Welshman Craig Bellamy's first-half strike would prove to be the winning goal and enough to seal an important win for GB.
But the Lions of Teranga, playing at their first Olympics, drew level with 10 minutes remaining through Moussa Konate's deft finish after he latched on to a defence-splitting pass.
There could have been even more late drama but Team GB substitute Marvin Sordell struck the crossbar, much to the despair of the passionate Old Trafford crowd.
It ensured a frustrating end to the match for Stuart Pearce's team, who were aggrieved by a series of physical challenges from their opponents.
The draw leaves Group A in the balance as GB prepare for their remaining games against UAE on Sunday and Uruguay next Wednesday.
The South American side, one of the pre-tournament favourites, defeated UAE at the same ground hours earlier and so, with only two teams qualifying from each group, there remains all to play for.
If the home team had grounds to feel aggrieved at the leniency of the referee, they could have no complaints about the level of support they received.
Old Trafford was packed well before kick off and GB were roared on to the pitch as they emerged from the tunnel.
There were chants of "GB" before the match and when the Group A encounter finally started Pearce's team enjoyed lots of early touches as they settled quickly.
However, it was Senegal who initially looked the more threatening, with the highly rated Ibrahima Balde failing to make the most of two early headed opportunities.
Pape Souare was powerful and direct down the left, while Micah Richards had to make two important interceptions after the African side turned the GB defence.
But it was GB who crafted the first decent opening, from which they scored. It was their first goal at the Games since the 1960 Olympics and one that was created by their three over-age players.
Giggs aimed a free-kick towards Richards, whose scuffed header was only half-cleared. The ball fell invitingly to Bellamy, who struck it into the ground and up into the net.
A huge cheer greeted the goal but GB were fortunate not to concede when a horrific clearance from Jack Butland was smashed straight at an unmarked Sadio Mane.
Thankfully for the young Birmingham keeper his desperate charge from his goal did enough to put off the Metz forward, who clipped his effort well wide.
GB did not seem as busy and bustling after the restart and Senegal were quick to try to take advantage.
Butland did well to save a snap-shot from Balde and, shortly afterwards, a crisp strike from Saliou Ciss, while Danny Rose was well positioned on the goal-line to clear a header from Abdoulaye Ba.
The crowd seemed to sense the shift of momentum and tried to lift the team, while several injury stoppages did little to help the flow of the game.
One followed a late tackle on the ever involved Bellamy by Ciss, and it led to a brief spate of pushing and shoving between Neil Taylor - himself the victim of a late first-half tackle - and Magaye Gueye.
But as the match moved into the final 10 minutes and GB seemed to be closing in on victory, the defence was undone by a pass that Konate converted with his precise finish.
Substitute Sordell, who replaced Daniel Sturridge at the break, hit the woodwork before Senegal's Konate pulled a strike wide at the other end.