Alonso says McLaren have only had one proper upgrade this season

McLaren driver Fernando Alonso says that his side have only introduced one single significant upgrade to its car this season.

This is down to its ongoing technical problems, according to Alonso.

McLaren have already admitted that their MCL33 car this season produces less downforce than last year's car, and Alonso said the team are "working very hard and very deep into the weakness of the car".

"First we identified them in race three, race four. In Barcelona we introduced a new package with a new nose and different things and we recovered a little bit the level," Alonso told RaceFans.net.

"So we performed well in Barcelona, in Monaco. But then we came back to our original problems and a lack of performance."

McLaren focused their attention on Friday pratice sessions on solving a fundamental problem with the car's aerodynamics which it didn't detect in wind tunnel testing.

"I think now after investing three or four Friday FP1s, doing just aero development and aero understanding, we know that maybe we compromised a little bit the race weekend and the performance in qualifying but we get a lot of information on those Fridays," Alonso explained.

"I think now we are in a point of we know exactly what to do."