Mercedes Formula 1 chief strategist James Vowles says that it's "unlikely" the team has resolved the tyre problems it experienced at Silverstone - despite a strong race in Spain.
After losing out to Max Verstappen and Red Bull in the 70th Anniversary GP, Mercedes undertook what Vowles calls "incredible work" to address its tyre blistering issues before the Barcelona event.
Lewis Hamilton scored a dominant win in Spain with Valtteri Bottas taking third place behind Verstappen, having not suffered tyre issues.
"Clearly following Silverstone, there was a lot of focus on the tyre, the tyre management and the overheating that we experienced during the course of that race, including the blistering," Vowles explained in a team video.
"We had but a few days to get on top of this, and clearly you are not going to change the car dramatically between those two events.
"Barcelona is slightly different, it's a higher downforce track, we run a bigger wing than we do at Silverstone, but other than that you are not going to fundamentally change the design of the car. So, you work with what you have, which is set-up and management."
Vowles admitted that it was hard to assess changes at a different venue.
"We highlighted that there were a few areas where we weren't quite optimum at Silverstone if we had to go back there, but the problem is, without racing at the same circuit and the same conditions, you can't validate that," he said.
"And as we went into Barcelona, there were a few tweaks on set-up and a few tweaks on how we were going to approach the weekend and use the tyres. I'm happy to say that the incredible work that was done over those, really just a few, days really paid off during the course of the race.
"We were managing the tyres, as was Verstappen, but when we needed a bit of performance it was there and available. And Lewis was just able to eke out a tenth at a time at the key points in the race.
"And really, it paid dividends. For Valtteri, the car that was following the other two in the dirty air for most of the race, and that's what makes overheating even worse, he was able to really bring it home, scythe through traffic, and even get just about within undercut range of Verstappen.
"That's an incredible change of where we were just seven days before."
However, Vowles conceded that the circumstances in Spain were different compared to Silverstone, and thus the team could yet experience problems at other venues.
"Now, the reality is, are the problems fixed? It's unlikely. The situation that happened at Silverstone is different to what we had in Barcelona," he said.
"We have to keep learning, we have to keep improving. But what I'm happy to report is that the conditions we had in Barcelona were some of the most difficult this year.
"It was as warm, it was as sweltering on track and the reality behind that is, we performed well in those conditions, and we need to keep improving and moving forward."