Leverkusen are missing seven regulars, but the damage is particularly acute in attack, where forwards Victor Boniface, Amine Adli, Jonas Hofmann and Martin Terrier are all missing.
Speaking ahead of Tuesday's home clash with Red Bull Salzburg on his 43rd birthday, the former midfielder -- who won several trophies across a glittering playing career with Liverpool, Real Madrid and Bayern Munich -- toyed with the idea of a return.
"If (Bayer Leverkusen CEO) Fernando Carro gives me a player contract, then maybe," Alonso joked, adding: "I've only got a contract as a coach and I'm not allowed to play."
Last season, Leverkusen won an unbeaten league and cup double, losing just one of 53 games -- the Europa League final against Atalanta.
"What happened last year was not common. We didn't have too many problems (with injury)," said Alonso.
The Spaniard has been forced to dig into the club's junior stocks, calling up four players 18 and under, including the 16-year-old Andrea Natali.
Leverkusen have won two and drawn one of their four Champions League matches and sit 13th in the table, two points off the top eight.
