Sebastian Vettel admitted to "mixed feelings" over Robert Kubica's return to the grid in 2019 with Williams. The Pole will race in Formula 1 for the first time in eight years next season, having recovered from life-altering arm injuries sustained in a rally crash.
Kubica served as Williams' test and reserve driver this year, having been overlooked for the race seat in favour of Sergey Sirotkin.
However, the Russian struggled to impress in a dreadful Williams car and finished bottom of the drivers' standings with a solitary point picked up at the Italian GP partly due to Romain Grosjean's disqualification.
Kubica will partner rookie George Russell in 2019, the Mercedes junior driver stepping up to F1 after winning GP3 and Formula 2 across the past two years.
Vettel debuted in F1 as a 19-year-old when filling in for the injured Kubica at the 2007 United States Grand Prix.
And the Ferrari man is concerned that Kubica's return could block a path for a younger driver – Esteban Ocon had been linked to Williams, for example – albeit countered against the delight at seeing the Pole complete his astonishing journey back to the sport.
"I have mixed feelings," Vettel told Blick.
"On the one hand, it pleases me personally. No one can even imagine how hard it was for him and what he went through.
"On the other hand, there are also young drivers who deserve a chance."