All-rounders Jacob Bethell and Will Jacks, who play for Royal Challengers Bengaluru and Mumbai Indians respectively, are expected to do the same.
The Titans, who are top of the IPL with three matches left, need only one win to guarantee a play-off spot.
Sri Lanka batter Kusal Mendis appears set be signed by the Titans as Buttler’s replacement. Their final group match is on 25 May.
Second-placed Royal Challengers also need to win one of their three remaining matches to qualify.
