Mansell's Lola-Cosworth was quickest in morning practice and second quickest, just 200ths of a second behind Paul Tracey's Penske, overall.
Emerson Fittipaldi and Al Unser Jnr were lurking just behind Mansell.
Then, in the last minute of the session, Fittipaldi shaved over two seconds off his best morning time, taking the provisional pole for tomorrow's sixth round of the PPG IndyCar World Series.
Mansell appeared very relaxed and pleased to be back on a street course. 'This is like a weekend off for me.' Mansell said 'It's great to be back on a track where you can make left hand and right hand turns, you need to break, some times charge into the turns, you almost lose it, you get some wheelspin, I mean it's a kind of racing that's nice.
'I'm really enjoying myself this weekend and I'm happy that I'm competitive.'
Mansell's car has trailed behind the leading Penskes for most of this season but for a time yesterday it looked as though the pattern would be broken. Mansell went out early in the day and recorded times that kept him within a second of the quickest Penske, piloted by Tracy. Then Bob Rahal, in a freshly-revised Honda engine, managed to squeak by Mansell's time while the latter was in the pits for some set-up changes.
However, when he came out for the next practice laps, Mansell went a full two seconds quicker than the Penskes' best.
Mansell was on pole here last year, but he skidded harmlessly off-course midway through the race, failing to finish for the first time that season.Reuse content