Thanks to Henry Hope-Frost we were reminded that today marks the anniversary of Riccardo's victory (the 50th for Williams) in the 1991 Portuguese GP. You can read the full race report here, but perhaps the weekend should also be remembered for Riccardo's pole position. Nigel Roebuck wrote about it in Autosport:

While not on the same page, week in, week out, as a Senna or a Prost, when the mood was on him Patrese was a magnificent racing driver, and my abiding memory of him will always be final qualifying at Estoril that year. Early in the session his own car blew up, and his behaviour was pure Latin theatrical as he stomped back to the pits. There the spare Williams sat, but, under the terms of Mansell’s contract, it was for his use alone. Not until the last five minutes of the session, when Nigel clearly wouldn’t need it, was Riccardo permitted to climb aboard.

There had no opportunity for set-up work, merely an educated guess or two, and the Renault V10 was of an earlier, less powerful, type, but Patrese had ire and adrenalin to spare that afternoon; after a single warm-up lap, he shoved Senna, Berger and Mansell aside, and put himself on the pole. “That was good, wasn’t it?” Patrick Head beamed afterwards, and he was even sunnier the next day, when Riccardo won the race.