Lotus team boss Eric Boullier believes Romain Grosjean is one of Formula One's top drivers after the Frenchman finished second in the US Grand Prix on Sunday.
The 27-year-old claimed his fourth podium position in five races and was the main threat to Red Bull throughout the weekend at the Circuit of the Americas.
Boullier was particularly impressed with the speed Grosjean has shown in the latter stages of the season and is confident that Lotus will be challenging for race victories in 2014 despite losing the services of former world champion Kimi Raikkonen.
"We've always known Romain is super fast, actually maybe too fast, and sometimes too fast for his car," Boullier said in reference to the crucial mistakes Grosjean was prone to earlier in his career.
"Having some completeness with his family [he became a father earlier this year] has helped him reach another level of confidence, and then you see the results on track.
"He is starting to be a damned good driver. I think you can rate him in the top three or four today.
"He started to perform well from Germany onwards. There was still a bit fine-tuning needed on his side, but he has had a very fine second half of the season.
"Now he will start next year in a different mood, and we will have a different perspective from him."
In fact, Boullier is of the opinion that Raikkonen's departure from the Enstone team has helped Grosjean, since the Finn's move to Ferrari has forced the former GP2 champion to take a more leading role within Lotus.
"It is a combination between him [Raikkonen] leaving and his personal life being settled, which brought him a lot of confidence," he added.
"That was maybe the kick he needed to take off."