KUALA LUMPUR, April 6, 2018 (Reuters) - Malaysia's Prime Minister Najib Razak announced the dissolution of parliament on Friday, paving the way for a general election showdown with his old mentor and the country's most seasoned campaigner, Mahathir Mohamad. Najib is under pressure to deliver an emphatic win for the Barisan Nasional (BN) coalition, as he struggles to appease Malaysians unhappy with rising costs and a multi-billion dollar scandal at a state fund he founded. The 64-year-old leader is expected to retain power due to a rift in opposition ranks between Mahathir's bloc and the Pan-Malaysian Islamic Party. But analysts predict a tough fight from Mahathir, who transformed Malaysia into an industrial nation from a rural backwater during his iron-fisted 22-year rule until 2003. The opposition says the election will be unfair.