Craig Bellamy netted after 20 minutes but Stuart Pearce saw his side denied three points by Moussa Konate's goal eight minutes from time.
GB were denied what seemed a certain penalty when Bellamy was crunched to the ground in the second-half and sub Marvin Sordell hit the crossbar late on but the physically uncompromising African side well full value for their point.
GB entered their first Olympic men’s football match in 52 years low on confidence after being outclassed by Brazil in last week’s warm-up and a Mexican wave in the near-capacity crowd indicated the paucity of chances in the opening 15 minutes.
But Bellamy, one of four Welshmen in the GB starting line-up, drove a shot into the corner of the net after a free-kick from captain Ryan Giggs fell kindly to the Liverpool man in the penalty area.
That was GB’s only shot on target in the opening period as Senegal had the bulk of the chances.
Sadio Mane spurned a golden chance to equalise after Jack Butland’s clearance went straight to the Senegal striker. He lifted his shot over the keeper but wide of the post.
Ryan Betrand and Steven Caulker made crucial blocks while Joe Allen and Micah Richards were forced into vital last-ditch tackles with GB’s only other sight of goal coming when a raking free-kick from Giggs found Daniel Strurridge but he was forced wide by keeper Ousmane Mane and screwed his shot wide.
The trend continued in the second-half and Butland was forced to get down sharply to his left to make a fine one-handed save to deny Ibrahima Balde.
Zargo Toure pinged a 20-yard effort narrowly over the top, Saliou Ciss warmed the fingertips of Butland from distance and Danny Rose headed Abdoulaye Ba’s free header off the line although it might just have been going wide.
Uzbekistan referee Ravshan Irmatov dished out four yellow cards to Senegal but was lenient to their physical approach and none more so when Ciss crunched into Bellamy with both feet in what seemed like a stonewall penalty.
It was a challenge that saw Bellamy, like compatriot Allen, forced off and shortly after Senegal were on level terms.
Both Richards and Caulker went up for the hosts’ first corner of the match and they never regrouped as a superb pass from Mane split open the GB defence and Maccabi Tel Aviv’s Konate calmly lifted the ball over the advancing Butland.
That set up a grandstand finish as a square pass from sub Aaron Ramsey was crashed against the woodwork first-time by Bolton’s Sordell, on at half-time for Sturridge.
Mane had a clear header from eight yards go well wide and Konate screwed a shot wide, just two of their 17 efforts on goal compared to GB’s five.
Britain can feel hard done by for the non-penalty however as they failed to match the achievement of the women's team who kicked off their campaign on Wednesday by beating New Zealand 1-0.
Britain next face UAE on Sunday who lost 2-1 to third favourites Uruguay in their opening match.