Lewis Hamilton admitted he was baffled by the incident with Fernando Alonso during qualifying for the Hungarian Grand Prix.
Hamilton, the rookie who leads the Spanish double world champion by two points with seven races remaining, completed an all-McLaren front row at a tight circuit where overtaking is extremely difficult.
The 22-year-old Briton had led until the Spaniard pipped him by 0.107 seconds with his final lap right at the finish - after blocking his rival in the pitlane for just long enough to prevent him making any reply.
Television images suggested Alonso was looking at his physiotherapist for a signal, with the man apparently counting off the seconds before being spoken to by team boss Ron Dennis.
Hamilton, who said he had slowed before pitting to ensure that he was not held up, had to sit helplessly in his car behind Alonso with the seconds ticking away and the Spaniard failing to move off.
The extraordinarily long wait left the Briton unable to get round the circuit in time to start a final flying lap before the chequered flag.
Alonso, facing pointed questions about the incident afterwards, said he had been told by the team to wait but was less forthcoming about the reason why.
"You can ask the team this question, because I am always monitoring the pitstop by the radio. They do the calculations, they find the gaps and I just drive the car," he said. "I am always ready to go, as soon as they put on the tyres."
Hamilton, whose relationship with Alonso has been distinctly edgy since he started beating the 26-year-old champion, was clear about how much the delay cost him.
"I was obviously told on the way in that Fernando was doing his stop and that I should back off so I didn't have to queue. That's what I did, so I saved some time coming round the last corner and into the pits," he said. "But for some reason he was just held there."
Asked how much more time he would have needed to cross the start/finish line before the end of the session, he replied: "About the same amount of time that I was held up in the pitstop.
"I really don't understand why I was held back. So I guess you should ask the team and I definitely will do when I go back and have a debrief," said the Briton. "It definitely needs a good explanation.
"I'm not angry. I'm curious as to what's gone on and I find it quite interesting and amusing," he added. "But the good thing is that we have the pace and we did a great job."