Karthik has been in superb form for Tamil Nadu this season as a finisher - he has scored 349 runs in six innings at an average of 87.25 and strike rate of just over 135.
The wicketkeeper was also not named in the squad for the upcoming series. After the announcement, rumours started circulating that the 32-year might announce retirement.
Sri Lanka have included veteran Lasith Malinga, who had opted out of the Pakistan tour, in the 16-member squad for T20Is against Australia.
Limited-overs captain Aaron Finch is battling to be fit for Australia's opening Twenty20 against Sri Lanka after picking up a side strain.
Shikhar Dhawan, on Karwa Chauth, posted a lovely message for his wife Aesha who lives in Australia with three children.
In August, RCB roped in Mike Hesson as their Director of Cricket Operations and Simon Katich as the new Head Coach.
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