Charles Leclerc made huge gains from Friday to lead FP3 at the Singapore Grand Prix and put Ferrari in the hunt for pole position at the Marina Bay Circuit.
Leclerc had ended Friday 1.3 seconds off the pace of Lewis Hamilton, but led the championship leader by two tenths in Saturday's early session.
Leclerc has found an extra two seconds overnight, although Hamilton's pole time 12 months ago was another two seconds quicker, ensuring qualifying is no foregone conclusion just yet.
Ferrari had been expected to drop back into the pack after Leclerc's victories in Belgium and Italy, but Sebastian Vettel was third-quickest, six tenths off Leclerc, to suggest that Ferrari's pace is genuine.
Hamilton will have more time to find, having toured Marina Bay a couple of times before setting his flying lap, having spun on his exit from the pits and finding traffic.
Toro Rosso and Racing Point have concerns after the session. Daniil Kvyat will take a penalty-free engine change for qualifying after an oil leak, while Sergio Perez's Racing Point needs repairs after shedding carbon fibre in a hit against the way at Turn 21 that brought out red flags.
That curtailed Max Verstappen's first flying effort and the Dutchman struggled to get going again upon the resumption and was 1.2 seconds off Leclerc at the chequered flag, having looked like Hamilton's nearest challenger on Friday.