Lance Stroll has conceded to surprise at the pace of Mercedes’ upgraded W14 during the Spanish Grand Prix, describing the car as “a rocket ship”.

Up until Sunday’s race at Barcelona’s Circuit de Catalunya, Aston Martin had proven to be the best of the rest this season behind dominant Red Bull.

But for the first time this year, the team was found wanting as Stroll and team-mate Fernando Alonso finished sixth and seventh.

Although Alonso’s result was a small improvement on his starting position of eighth – as a consequence of mistakes made in Q3 on Saturday – the two-time F1 champion lacked the performance to make any further inroads.

In contrast, George Russell rose to third from 12th on the grid, finishing behind team-mate Lewis Hamilton to give Mercedes its first double podium of the season.

“They (Mercedes) had a rocket ship,” remarked Stroll. “I’m not sure where they found that pace.”

At the race previously in Monaco, Mercedes unveiled its upgraded car, complete with a new front suspension, floor, and sidepods, prompting Red Bull team principal Christian Horner to describe it as “a B-spec”.

The weather conditions in Spain were also ideal for Mercedes, allowing it to operate in the right window for the car and tyre package combined.

Aston Martin struggled in contrast, with team principal Mike Krack to delve deep into the issues.

Stroll added: “I was a little disappointed when cars started passing us.

“We had a good start, settled into third, and I’d hoped we’d be able to keep good pace throughout the race.

“I was expecting us to be the strongest car after Red Bull. I expected, after all the races this year, to have the pace to do something good but we just didn’t have it.

“We suffered a lot with degradation relative to Mercedes, and Ferrari as well. They just had a quicker car.

“Red Bull is in another league. We just didn’t have the upper hand.”

Starting from fifth on the grid, Stroll rose to third on the opening lap, taking advantage after Hamilton had been clipped from behind by McLaren’s Lando Norris.

Despite then holding a gap over Hamilton, it was not too long before the seven-time F1 champion sailed by.

Explaining the situation, Stroll confirmed Mercedes was able to “look after their tyres really well”.

“Five laps into the race they just didn’t have any deg, and I just felt the tyres dropping off,” remarked Stroll. “They were pushing on.

“Looking at Russell’s race, I think they were able to do that all race. They seemed to have a really good car.”

For the first time this season, Stroll finished ahead of Alonso, although it could easily have been positions reversed as the Spanish driver had better pace at the end of the race due to him being on fresher tyres.

Alonso, however, made clear over the team radio he would not attack Stroll simply because no matter the order between them, they were bringing home the same number of points.

Alonso conceded after the race he did not want to go “crazy” and potentially risk a further incident after severely damaging the floor on Saturday when he ran over the gravel.

Appreciating Alonso’s decision, Stroll said: “We were sixth and seventh, bringing the car home and thinking about the constructors’ championship.

“We respect each other as team-mates and we want to score as many points as possible for the team, and in those situations, it sucks to have an accident over small-ish points.

“It’s about bringing the car back in one piece because all the guys that work super hard at the factory deserve that.”