Top Gun of fast serve Sam Groth remains undaunted in his quest for Top 100 status despite dropping his opening-round match at the Australian Open late Monday afternoon. The big-serving Aussie wild card fell to 28th-seeded Canadian Vasek Pospisil 6-4, 6-3, 6-4 in what Groth called his “worst match” of the season. Groth, who surged to a career-high No. 157 ranking after reaching his first ATP Tour quarterfinal at Brisbane two weeks ago, has been building on a successful 2013 campaign in which he made eight Challenger quarterfinals or better and won one Futures title. But on a scorching summer day, the 23-year-old Pospisil had too much game for Groth. The 6-foot-4 Canadian parlayed service breaks in the first and third sets, along with two in the second, into a comfortable 1-hour, 43-minute victory. “Today is disappointing. I’m sitting here right now and I’ve been off the court for probably 20 minutes,” Groth said. “I’m thinking, ‘Geez, I probably didn’t play as well as I wanted to today’. But I said to my coach (Ben Mathias), we spoke about it before, and we said we want to be winning matches like this. We don’t just want to be turning up and, after the summer, I genuinely believe I can get to top 100.” Last week in Sydney, Groth was two points from knocking out former world No. 8 Radek Stepanek in straight sets in a first-round encounter. Groth, who clocked a record-setting 163-mph missile at a Challenger event in 2012, served 16 aces to six for Pospisil, but only won an uncharacteristically low 67 percent of the points on his first serve. The Canadian won 90 percent of his first deliveries. Pospisil takes on Matt Ebden, another Australian, in the second round. Ebden edged Frenchman Nicolas Mahut in a five-set marathon immediately preceding the Groth-Pospisil match.