Cape Town - Swapping cars with NASCAR legend Jimmie Johnson, Fernando Alonso was impressed with the American's pace in a McLaren Formula One car.
Fresh from retiring from Formula One in the wake of Sunday's Abu Dhabi Grand Prix, Alonso was back behind the wheel at the Bahrain International Circuit on Monday.
He posted a benchmark time of 1:40.204 in a V8-powered 2013 McLaren before Johnson, a seven-time NASCAR champion, clocked a 1:40.462.
"Impressive. He was really gaining time every run," Alonso told Autosport.
"Sometimes you put new tyres on these cars for the very first time and you are not able to extract the grip, but he was able to guess this extra grip that the new tyres are giving to you, and extract that grip into lap time so I was very impressed with that.
"We were swapping the cars, having fun, but also we wanted to feel the new environment in a representative way and in a speed that we could feel something close to what they feel normally."
Johnson, though, had a few troubles on his opening laps before adjusting to driving a F1 car.
"Literally on the first outing, my helmet was trying to leave my head, and I was staring at the microphone in my helmet it was so high," he told ESPN.
"I was like, ‘I don’t want to stop but I think I should’.
"I got my helmet more under control, and then it was really my eyes trying to find their way far enough ahead and far enough round the turns..."
The swap included Alonso putting in the laps in Johnson's NASCAR Chevrolet with Alonso saying it was "fun" to drive.
"I knew that the cars were very basic in terms of technology," he said.
"Last time I ran an H-gearbox was in 1999, so it was going back a lot in time.
"The car was very powerful for the amount of grip available. Maybe with other cars around it is different but definitely alone it was a lot of fun."