By Renee Maltezou ATHENS (Reuters) - Alexis Tsipras was elected in January on a far-left platform, promising Greeks an end to five years of financial pain. Now, after seven rollercoaster months at the helm, Tsipras, 41, is asking voters for a second chance, in a tightly-fought election to decide who will lead Greece's angry and impoverished population through its third international bailout programme. For Sunday's vote, the telegenic Tsipras has moved to the centre-ground to buttress his support, saying he will implement the bailout while also introducing measures to cushion the impact of austerity.