Ryan Bertrand and Daniel Sturridge featured for Team GB as Senegal scored late on to salvage a 1-1 draw at Old Trafford.
Craig Bellamy had put the hosts in front after 20 minutes when a Ryan Giggs free-kick was headed straight into his path, but GB failed to kick on.
As a spectacle, there was little goalmouth action to speak of in the first-half, although Sturridge dragged one particular shot wide of the post as he attempted to latch on to a Giggs pass.
The Chelsea striker, whose participation in the tournament was in doubt until recently after he contracted viral meningitis, was withdrawn at half-time with Marvin Sordell replacing him.
Senegal improved after the break, but Stuart Pearce's side had a blatant penalty appeal waved away when Bellamy was brutally scythed down inside the penalty area, a decision which proved to be the turning point in the game.
Moments later, with only eight minutes left to play, Senegal scored the goal their second-half performance had merited when a quick break ended with Moussa Konate clipping his strike beyond the advancing Jack Butland.
As GB pressed for a winner in the dying moments, Sordell looked to have secured all three points as he met substitute Aaron Ramsey's cross, only to see his strike crash against the bar, before the referee blew for full-time.
Team GB are next in action on Sunday when they face UAE, who were beaten 2-1 by Uruguay in their opening game.
In what was clearly the most exciting game of the day, our newest recruit, Oscar [pictured above], was involved in a five-goal thriller as tournament favourites Brazil opened their campaign with a 3-2 win against Egypt in Cardiff.
The 20-year-old played the full 90 minutes and impressed throughout, laying on the first two goals for Mario Menezes' side in a scintillating first-half display.
A neat change of feet and slick pass allowed Rafael to open the scoring after 16 minutes, while shortly after he latched on to Hulk's flick, before rounding the goalkeeper and crossing for Damiao to double their advantage.
The game appeared to be over when Neymar made it 3-0 inside the opening half-hour, but goals from Aboutrika and Salah after the break set up a tense finish.
Chelsea duo Juan Mata and Oriol Romeu, meanwhile, were on the wrong end of a major shock in the opening game of the competition as Spain were beaten 1-0 by Japan at Hampden Park.
Yuki Otsu scored the only goal of the game in the 33rd minute following some poor defending by Spain, and their task was made all the more difficult nine minutes later when Inigo Dominguez was controversially dismissed for what appeared to be an innocuous challenge on Kensuke Nagai.
Mata, who played the full 90 minutes, was a central figure for Spain, particularly early on, and he almost broke the deadlock in the first-half, forcing Japan goalkeeper Shuichi Gonda into a smart save.
However, shortly after Otsu's opener, Hiroshi Kiyotake had a wonderful chance to double Japan's advantage only to fire wide after rounding Manchester United's David De Gea.
Romeu entered the action in the 63rd minute, replacing Malaga playmaker Isco as they looked to gain a foothold in the match.
As the game moved into its final stages, both Mata and Barcelona's Jordi Alba went close, but the victory was no more than an impressive, efficient Japan deserved.
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