Aprilia's Aleix Espargaro has been ruled out of the final MotoGP test of 2018 at Jerez after being hospitalised with gastritis, and will be replaced by test rider Bradley Smith.
Espargaro contested the first '19 pre-season test in Valencia last week, and was 10th on the combined times after two days of running on an upgraded RS-GP engine with a best lap of 1m31.400s.
Due to continue development work at a two-day test at Jerez starting on Wednesday, Espargaro has been ruled out from running after he was hospitalised with gastritis.
As a result, test rider Bradley Smith - who will join Aprilia's official test team in 2019 after losing his KTM ride to Johann Zarco - will take his place alongside the team's new signing Andrea Iannone.
Smith was due to ride at Jerez this week beforehand with the test team, just as he did in Valencia, and will have his role filled by former World Superbikes rider Matteo Baiocco, who handled Aprilia's testing duties this year.
Briton Smith heads to the Jerez test with two days of recent riding experience under his belt already, after taking part in three days of running at the Spanish venue last week aboard the SIC-run MotoE bike.
He topped the debut test for the all-electric machines with a 1m50.265s.
Earlier this week it was announced that Ducati test rider Michele Pirro will miss the Jerez outing to undergo surgery, and will be replaced by the Italian marque's new World Superbike recruit Alvaro Bautista.
Honda test rider Stefan Bradl, who rode in place of the injured Cal Crutchlow in Valencia, will be out on track on the RC213V at Jerez, but as part of the HRC test team - with whom he has already completed laps this week during the WSBK test on Monday and Tuesday.