Joe Allen believes Team GB's fitness will peak for their Olympic opener against Senegal on Thursday after the "perfect preparation" provided in their 2-0 defeat by Brazil.
Sandro and Neymar scored as Stuart Pearce's side made their 2012 bow.
Swansea's Allen said: "We feel when we go into the first game that's when we'll really start peaking in terms of fitness and in terms of preparation."
GB face pool rivals Senegal at Old Trafford on 26 July.
The Welsh midfielder, 22, played throughout the clash against Brazil and described the occasion as "a great experience".
He added: "It was an experience you won't forget and, I think, great preparation for us going into our first group game against Senegal.
"This is the test we needed and from a fitness point of view I think this is going to be perfect preparation for our first group game.
"And I'm pretty sure Brazil are going to be one of the top teams in this tournament so if we get a second chance to play them, then we'll be better prepared.
"Come the start of the Senegal game will probably be the time for us to start peaking.
"Ninety minutes was great for me to get under my belt personally.
"At this stage of the season it's obviously tough to do that, but I feel ready now to go into the tournament and play, hopefully, a big part."
Allen, one of five Welshmen in the GB squad along with skipper Ryan Giggs, Craig Bellamy, Aaron Ramsey and Neil Taylor is also one of three Swansea City players involved.
But while he, English winger Scott Sinclair and defender Taylor prepare for their tilt at Olympic gold, their club-mates are preparing for the forthcoming Premier League season on a three-match tour to the United States under new manager Michael Laudrup.
The first of those games is against Colorado Rapids, kicking off at 02:00 BST on Wednesday, 25 July.