Germany international Tah, who had been nursing a cold, missed their midweek win over Mainz 05 that stretched their winning run to seven straight matches in the Bundesliga, the longest in the league at the moment.
But Alonso said Tah was ready to be part of the starting lineup on Saturday. For teammate Boniface, who is recovering from a muscle injury, the game was still a bit too early, with the Nigerian racing to be fit for next week.
Boniface, who has scored six league goals, has been out since late November with a thigh muscle injury.
"His development is good. He trained a bit but he is not in the squad (for Saturday). He needs time to train and get fit but his development is good."
Leverkusen, who take on Atletico Madrid in the Champions League next week before facing RB Leipzig in the Bundesliga, are currently in second place on 38 points, four behind leaders Bayern Munich.
"There is a chance (for Boniface to play next week). We will see, we have to wait. His feeling is good. For tomorrow it is still a bit too early but for next week, yes, there is a chance," Alonso said.