Concern is growing within Red Bull that Max Verstappen will leave the team at the end of the year, according to motorsport adviser Helmut Marko.

Red Bull's early-season struggles amid setup concerns have the team scrambling for ways to improve after four-time Formula One world champion Max Verstappen finished in sixth place Sunday in the Bahrain Grand Prix.

After the first two practice sessions at the Bahrain Grand Prix, Verstappen is again sounding the alarm. Verstappen sat out the first practice session, as Red Bull handed over driving duties to reserve Ayumu Iwasa to satisfy one of four required rookie driving sessions on the season.