Djokovic slips into Belgrade quarterfinals

BELGRADE, Serbia, May 6 (UPI) -- Hometown favorite Novak Djokovic battled through a straight-set victory Thursday in second-round action at the Serbian Open clay-court tennis tournament.

The top-seeded Djokovic, despite four double faults and four service breaks, came through with a 6-4, 6-4 victory over Fabio Fognini and moved into the tournament quarterfinals.

His opponent will be Serb countryman Filip Krajinovic, who is coming off a 2 1/2-hour 6-3, 1-6, 7-6 (7-5) victory over Horacio Zeballos. Krajinovic dropped serve more often -- four times compared to three for Zeballos -- and won just two more points (107-105) in advancing.

Also Thursday, No. 2-seeded John Isner, behind 16 aces, powered his way past Josselin Ouanna 6-2, 6-4 and Richard Gasquet ousted eighth-seeded Andreas Seppi 4-6, 6-2, 7-5.

Seppi and Isner will be quarterfinal opponents Friday.

The other Friday matches have third-seeded Sam Querrey against Igor Andreev and No. 4-seeded Stanislas Wawrinka versus sixth-seeded Viktor Troicki, another Serbia player.