Villeneuve expressed relief that the failure of the front-right disc on the Vanwall-Gibson Vandervell 680 with just over an hour of the race to go happened at Turn 10.
“Having that happen at Turn 10 was certainly better than at Turn 1,” Villeneuve told Autosport. “It’s never nice to lose the brakes, but it was probably a good place to have a failure like that.
“I knew what had happened, [I] was thinking that I shouldn’t hit the barrier too hard.”
The Vanwall emerged with only light damage from the rearward impact with the barriers.
Villeneuve revealed that he had been nursing a brake issue through his stint after taking over the car he shared with regular team-mates Tom Dillmann and Esteban Guerrieri.
“The brake pedal was getting long and through the whole stint it was getting worse and worse,” he explained.
“I was having less and less front brakes and was getting sideways in the corners.
“It made the driving difficult and then it [the disc] just blew.”
The ByKolles-run Vanwall Racing team was unsure of the reason for the failure in the wake of the race.
Head of operations Boris Bermes said: “The only thing we can say that it was clearly a brake issue, but we were not the only ones struggling with the brakes today.”
Portimao was the second time that Villeneuve has had an incident in the Vanwall.
He suffered rear suspension failure in the Sebring season-opener last month, which team owner Colin Kolles explained resulted from procedural issues inside the team.
The Vanwall also lost time with a penalty and an electronic glitch that forced Villeneuve to undertake a stationary reset.
Villeneuve said that the team was disappointed not to take a step forward on its Sebring performance.
“Sebring was always going to be difficult with the bumps, but we thought we should be more competitive here,” he explained. “But we weren’t quick today.”