The Tottenham Hotspur defender has spoken highly of the 19-year-old.
Indeed, Bentaleb was known within the Tottenham squad already for his ability during endurance running but Dier says the new signing is proving his match in practice.
He told Tottenham's official site: "Everyone has done well and it's good we're pushing each other, it really helps.
"Dele Alli and Nabil Bentaleb have been really impressive in the endurance running. Everyone knew about Nabil but Dele seems to be getting close to him so it’s been interesting! He's put up a good test!"
Making an impact?
Alli's fitness is impressive considering his age of just 19, although Bentaleb's young years suggest Tottenham's younger players are simply better with natural fitness at these early stages of the season.
Alli's stamina, however, will be music to boss Mauricio Pochettino's ears, as the Spurs head coach's mantra - with the Argentine often criticised for being one dimensional here - is fitness, fitness, fitness.
It remains to be seen whether the teenager can settle into Tottenham's first team in only his first season at White Hart Lane. A loan move at some point surely looks likely.
But, if Alli is already making an impact, there is no reason he can't make an early breakthrough as soon as next term.