British qualifier Dominic Inglot put on a battling performance in his first round clash against top-seeded Fabio Fognini at the St Petersburg Open before falling 6-4 6-4.
Inglot, who has a doubles ranking of 33, reached a Grand Slam quarter-final for first time at US Open with his partner Treat Huey last month.
And the 27-year-old used his 6ft 5in frame and powerful serves to more than worry his Italian opponent.
However, the world No 17, who was runner-up at the event in Russia last year, broke Inglot early in each set and saved the only break point he faced late in the second set.
Fognini is looking for his third career title having won his first two back-to-back in June.
Guillermo Garcia-Lopez of Spain, who is also looking for his third career title, defeated Russian qualifier Mikhail Biryukov 6-4 6-1.
Eighth-seeded Denis Istomin of Uzbekistan eliminated Samuel Groth 6-4 3-6 7-5, breaking decisively on his first match point when the Australian qualifier returned his forehand long.