Congress candidate Rajinder Rana, who has learnt political lessons for years from his once-mentor and BJP's Chief Ministerial candidate Prem Kumar Dhumal, on Monday "taught" him a lesson in return by defeating him in the Himachal Pradesh assembly elections.Rana defeated two-time Chief Minister Dhumal in a straight contest by 2,933 votes in the Himachal Pradesh's Sujanpur, the seat he was asked to contest from.Rana, a known social worker in the area, was once the election managera of Dhumal and he knows his family well."In politics one faces a defeat while another faces a win. It will be failure on our part not to be able to give justice to the people (of Sujanpur). It's time for introspection," an emotional Dhumal told reporters in his hometown Hamirpur.Dhumal had swapped his present Hamirpur seat, the pocket borough of the BJP, with party legislator Narendra Thakur, who won the seat.Political observers told IANS the contest was interesting between Dhumal and Rana, who had defected from the BJP, as the latter knows the inside-out of Dhumal and his family.Dhumal was contesting for this seat for the first time, while realtor-turned-politician Rana won it in the 2012 assembly polls as an Independent candidate by a margin of 14,116 votes.Later, he vacated the seat and unsuccessfully contested the 2014 Lok Sabha elections from Hamirpur as a Congress nominee. The vacated Sujanpur assembly seat was won by the BJP's Narender Thakur, a Congress rebel.