Barcelona head into Matchday 4 as the only team with a perfect record in the 2026/27 campaign after Real Madrid suffered a 1-0 defeat against Real Betis on Friday.
The result gives the reigning champions an early opportunity to open up a gap at the top of the table with another victory.
The main question surrounding Flick's team is the fitness of Lamine Yamal, who did not train with the squad on Saturday and is now a doubt for the trip to Valencia.
There is better news regarding Rodri, however, with the midfielder in line for his first start since joining Barcelona from Manchester City during the transfer window.
Barcelona paid 76.5 million euros, including add-ons, to sign the Spain captain, beating competition from Real Madrid for his signature.
The 30-year-old has been carefully managed since arriving at the club. He joined pre-season late and had previously undergone a minor back procedure, meaning Barcelona have taken a cautious approach to his return to full fitness.
Rodri missed the opening league match against Elche but came off the bench against Athletic Club and Rayo Vallecano, playing just over 50 minutes across the two games.
He has since been following an individual training programme designed by Barcelona's fitness staff to accelerate his return and help him adapt to Flick's system.
There had been suggestions that Flick could save Rodri for Barcelona's Champions League opener against Feyenoord next week. However, the midfielder now appears ready to step up from the bench and make his first start in Barcelona colours at Mestalla.
The match would also carry extra significance for Rodri, as it is set to mark his 100th La Liga appearance.
Real Betis produced a dramatic 1-0 victory over Real Madrid on Friday at the Estadio de la Cartuja, bringing the visitors' perfect La Liga start under Jose Mourinho to an abrupt end.
Ferran Torres has revealed that his decision to leave Barcelona for Paris Saint-Germain was made well before his European summer transfer, with the forward admitting he was eager to join the European champions.
Real Sociedad missed the chance to record consecutive La Liga victories for the first time since January after being held to a goalless draw by Celta Vigo on Thursday.
Marcos Llorente has retired from international football at the age of 31, bringing his Spain career to an end after 27 appearances.
