Rafael Nadal has the ‘highest motivation’ to get off to a good start as he looks to defend his Australian Open title.The Spaniard made a perfect start to last season in Australia, winning 12 consecutive matches and winning both the Melbourne ATP 250 and the Australian Grand Slam.Speaking ahead of the inaugural United Cup, the 22-time Grand Slam winner spoke of his excitement and motivation to kick-start his season well again.“Always the beginning of the season is exciting,” Nadal told atptour.com.“For everybody [it] is a new thing, all the doubts, how things [are] going to go. Even if I don’t know how many seasons I have on the Tour, beginnings are always diff …