Martin Guptill hit the fastest half-century by a New Zealand batsman, only for Colin Munro to better it moments later as the hosts needed just 10 over’s to rout Sri Lanka by nine wickets in their T20 match on Sunday, winning both matches of the series.Munro's half century, which included seven sixes, was the second-fastest in all T20 internationals, behind only a 12-ball 50 by India's Yuvraj Singh.