The Rossi show
Behind that show of outright pace from the Frenchman's Yamaha, Rossi's two and a half tenth deficit was nevertheless enough to put the Italian into P2 despite a crash earlier in the day - and Dovizioso was just 0.055 off his compatriot.
In fourth, Cal Crutchlow (LCR Honda Castrol) was the fastest Honda with a 1:54.457 - continuing his fantastic preseason form - after putting in 57 laps, which was the most of the top five.
Locked out
Two Ducatis locked out the top ten overall, with Danilo Petrucci (Alma Pramac Racing) just 0.009 off Rins ahead of him and 0.033 ahead of the Ducati Team machine of Lorenzo.
Lorenzo, who went fastest in Sepang with the quickest ever lap, put in a 1:54.692 in Qatar for P10. Second Alma Pramac Racing rider Jack Miller, who headed out late with a soft tyre for a time attack, was P11 overall and another tiny margin made the difference - just 0.057.
Completing top 15
The man completing the top fifteen was Aleix Espargaro (Aprilia Racing Team Gresini), after an early foray much further up the timesheets.
The elder Espargaro brother did a 1:55.232 on the last day, with the Noale factory having four 2018 RS-GPs in Qatar for the first time ahead of the first race of the year.
Wet testing
After the end of the dry track time, there was one last thing on the pre-season agenda - a wet test.
After everyone was back in pit-lane, crews around the venue set about getting the track wet in order to test Losail both in the wet and under the floodlights. After another, shorter session in those different conditions, the curtain then came down on the pre-season.
The MotoGP riders will enjoy a two-week break before re-assembling at the floodlit 5.3km circuit for the season opener on March 18.