Stoner, who fell at high-speed on Friday, went off track twice during Sunday's race on his way to eleventh position, but claimed to make clear progress towards solving his front-end problems as he rode to third place at the test.
The 22-year-old's best time on qualifying rubber was 0.539secs behind fastest man
Jorge Lorenzo - Stoner had been over one second from the Yamaha rider in Saturday's qualifying session - while Casey's 1min 40.588secs on race tyres was 0.8secs better than he'd managed during the race.
"We've done a few different tests on the setting and with the tyres and I'm pretty happy with how it's gone," declared the Australian. "We tried some different front tyres that gave me a better feeling than I had in the race yesterday, especially under braking, so I can say it was a really positive test.
"It's a bit of a shame because with just a few small changes to the set-up we had yesterday the situation has improved a lot and we could have had a much better race if we'd gone with this in the first place.
"The test on qualifying tyres didn't go quite as well because on the best one I ran wide in one corner and without that I would have knocked a few tenths off my best time. It has been the best day we've had at
Jerez and it's left me with a good feeling going to Estoril!" concluded the Qatar winner.
Stoner's team-mate
Marco Melandri is in bad need of a breakthrough after a torrid start to the 2008 season, but was forced to finish testing early on Monday after suffering a minor hand injury.
Melandri was not seriously injured in the accident, escaping with damage to a nail on his left hand, and felt he had been making progress prior to the fall, having already lapped 0.4secs inside his best race lap.
