Alex Lowes says he leaves Thailand thoroughly downbeat after his breakthrough on the Pata Yamaha was thwarted by a technical issue during race two.

Having made steady but slow progress with the YZF-R1 machine on the opening two days at the Chang International Circuit, Lowes and team-mate Sylvain Guintoli looked to have uncovered a competitive rhythm in Sunday's race with the pair challenging inside the top five over the opening third.

However, misfortune struck Lowes down at the midway point when a technical issue plagued his machine and he was forced to retire early.

"I'm really disappointed as I felt great on the YZF-R1 and had a decent start to run fifth," Lowes said. "Sylvain passed me on the third lap - we came together and ran off track - so I sat behind him, pacing myself for the next few laps - because I knew from yesterday's race that I had good pace near the end and could aim at fifth position.

"I was probably riding the best I have done all year, so it's even more disappointing that I couldn't finish the race. I'm pretty devastated, but I felt like I was riding really well and starting to understand how to get the best from this bike, so I need to go back, regroup and come back strong in Aragon."

Guintoli, who finished the second race in sixth, was encouraged by Pata Yamaha's huge gains overnight having slashed the time deficit to the leaders at the chequered flag from 25 to 13 seconds and feels the rate of improvement leaves the team in a good position approaching the European stint of the season.

"I said after Phillip Island that I thought we would struggle more here, and we did," Guintoli admitted. "But saying that we've shown some really good pace on pure lap time and pure performance, so that's a good sign. We've also progressed a lot during the weekend and in between the races - with a lot of work and a very late night working on data with the guys, so thanks to them for that."