Mercedes technical director James Allison admits that Kimi Antonelli's recent DNFs are a "bitter pill to swallow".

The youngster retired 44 laps into his home race at Imola with a throttle control issue, while it was his engine failure last weekend in Spain that brought about the Safety Car period that ended in controversy.

At Imola he was running eighth at the time of his retirement, while last weekend he was in seventh and closing on a struggling Lewis Hamilton.

"Kimi's young and full of all the optimism of youth," says Allison in the latest Mercedes debrief, "but I absolutely know that our failures in this period have taken a few chunks out of Kimi along the way.

"Two DNFs, one caused by a chassis problem, one caused by a PU problem in just three races, that's a pretty tough pill to swallow," admits the Briton.

Despite the failures, and unlike some, the youngster has maintained his composure on both occasions and not thrown a hissy fit.

"Leaving that aside, and Kimi looking in at himself, he will know that he's got more to find," says Allison. "But in amongst that, there's been a lot of very positive work with him and brilliant experience for him running on a very dynamic track like it was in Barcelona, with the track temperatures pushing up towards 50 degrees and managing soft tyres in those conditions.

"That is just putting experience into him at a very fast rate, and he was handling it pretty well."

The youngster is set to face further frustration later in the season, for the Barcelona engine failure is almost certain to lead to a grid penalty when he exceeds his power unit allocation later in the season, possible even at Monza.

"It puts some pressure on the pool," says Allison. "We could put in a new power unit next race weekend, suffer no penalties, because we're still below the maximum number you're allowed to use in a year without penalty.

"But, of course, we're only about a third of the way through the year, so that's going to put quite a strain on the remainder of the pool if we have to eke it out until the end of the year.

"So, we'll be just eyeballing up how to marshal those remaining resources in a good way. But, yes, it's obviously no fun when a power unit comes out of the pool before delivering its full life."

Following the overwhelming disappointment of Monaco, when neither driver finished in the points, Mercedes changed its set-up philosophy, a move which appears to have paid off.

"I think the most important thing of these three races was we got the first couple pretty wrong on the way that we set the car up," he admits. "Asked too much of the rear axle, and suffered badly as a consequence, so we approached Barcelona with something of a different mind-set.

"And on a track which would have murdered our tyres if we'd gone at it like we did in Imola and Monaco, we actually were a bit more ourselves.

"So, looking forward and knowing that we can do more of that and lean deeper into that in the races ahead, I think that's a good thing."