"If Advani has any doubts, he can come to me (Matoshri, Thackeray's residence in Mumbai) and I will give him a dose of morale and strength," Thackeray said in an edit in the party mouthpiece Saamna.
The comments followed Advani's latest blog in which he predicted a non-Congress, non-NDA alliance coming to power.
"This is like a general saying before a war that there is no guarantee on the outcome, and demoralising the entire army," Thackeray said, asking the National Democratic Alliance "not to lose heart" and to prepare for the general elections with renewed vigour.
Hinting that Advani's thoughts may have arisen on account of two contenders for the prime minister's post within the NDA -- Bihar Chief Minister Nitish Kumar and Gujarat Chief Minister Narendra Modi -- Thackeray said the issue could be sorted out after the elections.
Thackeray said the next prime minister should be from the NDA and that decision could be taken after the elections are over. "No point conceding defeat now, without even entering the boxing ring."
"Even Advani himself has been a prime ministerial contender over the years and if there is consensus, his wish can also be fulfilled," Thackeray said.
He also said that by his statements, Advani would add fuel to the fire of ambitions in Nitish Kumar and Narendra Modi for the prime minister's post.
Making the Shiv Sena's intentions clear, Thackeray said it would play "free-style wrestling" and even kick and knock down its opponents if required.
He urged Advani to help bury the Congress instead of playing politics through blogs and sending a wrong message down the ranks.