"I am absolutely delighted to be joining Manchester City", Mendy said on the club's website.
"But as the transfer window draws to a close next month, the strength of Arsenal's resolve will be put to the ultimate test".
Nasri who spent last season on loan at Sevilla was a surprise inclusion in Manchester City's squad for their pre-season tour of the United States.
However, for all the teams attacking talents, he inherited a leaky defence.
Guardiola has issues to address at both ends of the field, starting at the back.
En duda el futuro de Ben Affleck como Batman
El involucramiento de Ben Affleck en la eventual película en solitario de Batman ha sido disminuido cada vez más. Este cambio comenzará a tomar forma en las próxima películas de DC.
Completed a controversial switch to the Etihad Stadium in 2015 after making it clear to those at Liverpool that he no longer wished to be part of the long-term project at Anfield.
It was certainly a necessary signing given Gael Clichy was released this summer, while Aleksandar Kolarov was sold to Roma this week as Pep Guardiola was left well short of full-back options in general. He quickly became one of the best players of the French champion and one of the most flamboyant fullbacks in football.
Managed nine goals in his debut season in England, with his pace and trickery coming to the fore as he grew in confidence across the 2016-17 campaign. "He wants regular first-team football before the World Cup next summer". He is very unpopular due to his arrogant attitude.
After spending one season at Monaco Benjamin Mendy made the move to Pep Guardiola's side, becoming the world's most expensive defender. But for now, the honour belongs to Mendy, with his transfer fee eclipsing the £50 million Chelsea paid Paris Saint-Germain for Brazilian centre-back David Luiz in 2014.
"For such a young player, he has a wealth of top-level experience", Begiristain said. In doing so, he became the club's third youngest ever player to be named in a match day squad.