Bundesliga champions Bayer Leverkusen are sweating on the fitness of key player Florian Wirtz who has suffered an ankle injury while on international duty. Wirtz, 21, had to be substituted at half-time of Germany’s 1-0 Nations League win over the Netherlands on Monday night. Coach Julian Nagelsmann said that Wirtz got caught in the turf with his foot and appeared to have damaged an ankle ligament. “I hope it is nothing serious,” Nagelsmann said, with further examinations scheduled on Tuesday. Leverkusen face in-form Eintracht Frankfurt in the Bundesliga on Saturday and visit Stade Brest in the…