Great Britain men's football coach Stuart Pearce says his side will improve for their opening game at the Olympics against Senegal after
being soundly beaten by Brazil.
Sandro and Neymar scored in the first half to earn Brazil a 2-0 victory in the warm-up match at the Riverside.
"Next week is the most important one for us," Pearce told BBC Sport.
"Brazil are a very good side and well ahead of us in terms of games together and fitness."
Pearce's team face Senegal at Old Trafford on Thursday before they play United Arab Emirates and Uruguay in Group A.
But they will need to improve if they are to make sure of their passage to the knockout stages of the competition, having registered only one shot on target against an experienced Brazilian team.
Team GB's fixtures
v Senegal at Old Trafford
v UAE at Wembley
v Uruguay at Millennium Stadium
"We played against one of the most outstanding Olympics sides and they are one of the teams to knock over in this tournament if you are going to win," Pearce added.
"We have to take positives; we passed well up until the final third but we gave a couple of sloppy goals away.
"We knew where we were fitness-wise and we need a bit of punch in the final third and maybe this will come with fitness. We will be ready next week, we aren't ready at this moment in time."
After a positive start by Team GB, Brazil took charge of the contest and once they opened up a 2-0 lead, appeared to reign in their attacking threat.
Despite the result, GB captain Ryan Giggs remains confident his team-mates will show their quality during the Games.
GB suffer warm-up loss to Brazil
"We have only been together two weeks and we are getting better and better and we will improve as the tournament goes on," he said. "It was a good benchmark for us."
On the team's fitness the 38-year-old added: "It's a difficult balancing act because you want all 18 players to be fit... but you can't kill everybody in training.
"This game will bring us on and we have six days to get ready for Senegal. We have a lot of talent in the dressing room, everyone is comfortable on the ball and we will get better, I've seen it in training. It's disappointing to lose but we will take the positives out of it."