Britain beat Uruguay to reach last eight
Daniel Sturridge's goal on the stroke of half-time was enough to give Britain, back in the tournament for the first time since 1960, top spot in Group A and a last eight meeting with South Korea back at Cardiff's Millennium Stadium on Saturday.
He slid the ball home from close range after good approach work from Joe Allen and, although they came close to scoring several times, Uruguay, who last competed in the Olympics when they won their second gold in 1928, could find no response.
Their nearest effort came when Gaston Ramirez smashed the ball against the bar with a long range shot in the fifth minute of stoppage time.
"Today has been a fantastic day for Britain at the Olympics winning our first golds and we are happy to play our small part in that success this evening and delighted to get to the next stage," Britain coach Stuart Pearce told reporters.
Uruguyan coach Oscar Tabarez lamented: "We have a fine history in this competition from before, but it is a hard competition to win. It is so intense. We were not at our best, but Britain defended very well, especially their goalkeeper Jack Butland."
Britain finished top with seven points ahead of Senegal, on five after their 1-1 draw with United Arab Emirates in Coventry.
Uruguay finished third with three points and were eliminated along with the UAE who picked up just one point.
Britain has not competed in the Olympic football tournament for 52 years, mainly for political reasons involving the independent status of Wales, Northern Ireland and Scotland within world governing body FIFA.
Fears that the national anthem would be booed by the Welsh crowd came to nothing with a stirring rendition but the crowd were hugely disappointed before kick-off when the team was announced and Britain's skipper, Cardiff-born Ryan Giggs was not in it.
The former Wales international, who on Sunday at the age of 38 years and 243 days became the oldest man ever to play in the Olympic football tournament, was on the bench nursing a hamstring injury, but in his place another Welsh veteran and over-age player Craig Bellamy took the armband.
Britain, fielding four Welshmen in their starting line-up, settled first, with one of that quartet, Aaron Ramsey showing the way with a superb performance in central midfield that tipped most of the play Britain's way.
Uruguay, though, threatened throughout and were dangerous in the closing stages.
Luis Suarez and Edinson Cavani, who were expected to be among the goals for Uruguay throughout the competition, had another frustrating night with both high-profile club players frustrated by the impressive young British keeper Butland.
The pair did not score a goal in three matches.