Tyrone Edgar powered to a fine 100m win as Britain impressed on the track in the European Cup in Annecy, France.
Edgar, 26, dominated from the blocks to finish in 10.20 seconds to help GB's men end the first day as group leaders.
Martyn Rooney made it a 400m double, after Nicola Sanders, running her first race this season because of a knee injury, cruised home in 51.17 seconds.
Other GB victories included Jenny Meadows (800m), Mo Farah (5,000m) and the men's 4x100m relay team.
Edgar was also part of the relay team, which included Marlon Devonish, Christian Malcolm and Rikki Fifton, that won after the disqualification of the Germans.
After becoming the seventh British winner of the 100m in the history of the event, the 26-year-old US-based Edgar told BBC Sport: "It makes me feel good.
"I've been training hard this year - the hardest I've ever trained. I didn't really feel nervous but I just wanted to run and not hear about the pressure. I am very confident going into the Olympics trials."
Edgar's efforts helped Britain secure a three-point lead over Poland going into the final day.
Britain's women, competing in the top flight following their promotion last year, finished the day in third with Sanders taking a leading role on her return to competitive action.
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"This is my first race of the season, so it's good to start with a victory and my time is better than last year in my first race," she said.
"I really wanted to have this competition behind me, be successful at my first race and think about the next step.
"I'm confident everything's going to be in place at the right time."
Rooney, Europe's number one 400m runner this year, put in a strong finish to pull away from the field to win easily in 45.33s.
"My main aim was just to win and I always made sure I had something in the tank so I'm happy," said the 21-year-old.
"Endurance has always been my strength but to run 44s you have to go out harder and that's what I'll be working on leading up to Beijing."
In the 800m, Meadows blew away her opponents in the final stretch to win a stunning race in 2:01.20, while Helen Clitheroe battled well to grab second in the 3,000m.
Goldie Sayers struggled in the javelin and could only throw 57.76m to finish fourth while team captain Natasha Danvers finished a disappointing seventh in the 400m hurdles.
Farah, 25, performed excellently in the 5,000m to cruise home in 13:44.07.
"I felt comfortable but at the same time the conditions were hot, so I just waited until the last four laps.
"I've been working hard in training with my Kenyan friends and it's going well at the moment."
Tom Lancashire made a strong start in the 1500m, but had to settle for fourth, Chris Tomlinson could only leap 7.89m in the long jump to also finish fourth while Samson Oni was fifth in the high jump.
On Sunday, Phillips Idowu (triple jump) and Andy Baddeley (3,000m) are all good prospects for the men, while world 400m champion Christine Ohuruogu will be a strong favourite in the 200m, and heptathlete Kelly Sotherton is in the 4x400m relay squad.
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