Eighth seed Denis Istomin battled past Aussie Sam Groth 6-4, 3-6, 7-5 Tuesday afternoon in the first round of the St. Petersburg Open. The 27-year-old Istomin, ranked No. 47, was coming off a successful run at the U.S. Open, where he reached the fourth round before losing to Andy Murray in four sets. Groth, holder of the mark for the fastest recorded serve (163 mph), won three qualifying matches to reach his third Tour main draw of the year. Today he came within a break point of serving for the match at the Peterburgsky Sport Complex. Istomin, a native of Russia whose family moved to Uzbekistan when he was three months old, reached a career-high No. 33 ranking in August last year. With both players possessing big games, the matchup figured to feature some slam-bam tennis. And it did. Surprisingly, each struggled on his serve in the first set. Istomin won just 44 percent of the points on his first serve, while Groth was even worse at 30 percent. Strong returning had a lot to do with that. The 6-foot-2 Uzbek took the opener with three service breaks, while Groth had two. Service prevailed in the second set until Groth broke in the eighth game and then served it out to even the match at a set apiece. The 25-year-old Aussie, ranked No. 210, broke again in the opening game of the deciding set and jumped out to a 3-1 lead. Istomin got the break back in the sixth game and saved three huge break points in the 11th. The Moscow resident sealed the victory in one hour and 45 minutes by breaking in the next game. Groth hit 10 aces to three for Istomin and actually won one more point, 84 to 83, in the ever-so-close match. Istomin had 39 winners to 31 for his opponent and won five of six break points while Groth cashed four of eight.