It said that the first big challenge Fadnavis government will face will be the floor test and enquired if the BJP plans to overcome it by resting on the back of Shard Pawar-led NCP as it will raise questions about its credibility.
"You (BJP) have come to power by promising to convert Maharashtra into a corruption free and a Congress-NCP free state.
"You (Devendra Fadnavis) come from the Vidarbha region where the NCP had carried out a huge irrigation scam. By taking NCP's support from the very beginning, questions have arisen on the sanctity of your government," the Sena said in an editorial in its mouthpiece 'Saamna' on the eve of swearing-in of the BJP government.
"The biggest challenge for BJP right now is to prove a majority in the Vidhan Sabha. It is okay to say that you will form a minority government and even manage to run it. But running such a government is against the Constitution.
"(Sharad) Pawar has extended support without being asked for it, but will the (Devendra) Fadnavis government run with the help of Pawar's support" the Sena said.
Sena, however, expressed pleasure over Fadnavis leading the state and said that it is a matter of pride that Maharashtra is once again being led by Vidarbha and that it is responsibility of Fadnavis to fulfill people's aspirations.
"It should be kept in mind that Maharashtra needs a stable government and a stable CM. The son of Vidarbha's soil will now be leading the government and we believe that he will always keep his feet firmly on the ground.
"The state can now expect 'acchhe din' with Narendra (Modi) at the Centre and Devendra in the state. We welcome Fadnavis as the new chief minister," the Sena said.
After a bitter split ahead of Maharashtra polls, leaders of BJP and Shiv Sena, which remains an NDA constituent, have made conciliatory noises in recent days.
BJP's strength in the 288-member Assembly has come down to 121 after the death of an MLA. Sena has 63 members.
Sharad Pawar's NCP with 41 MLAs has already offered crucial outside support to BJP and said it will abstain from voting if the new government has to face trust vote to prove its majority.