MADRID – Serena Williams marked her first European appearance of the season with victory on the Madrid Open’s striking blue clay courts on Monday, but her sister Venus crashed out in the second round.Holder Petra Kvitova also started well as the third seed defeated New Zealander Marina Erakovic 6-2 6-3. Towering Czech Kvitova beat Victoria Azarenka in the final last year before going on to win the Wimbledon title.The only seeded player to fall was number 15 Jelena Jankovic who went out to Spanish wildcard Carla Suarez 4-6 7-6 6-4 in the first round.Serena Williams, who reached the third round the last time she played in Madrid in 2010, powered past last week’s Budapest Grand Prix runner-up Elena Vesnina of Russia 6-3 6-1.The ninth seed delivered some powerful serves, hitting 14 aces to set up a meeting with another Russian, Anastasia Pavlyuchenkova, in the next round."I was feeling good,” Williams told reporters. "It’s my first tournament in Europe this year and I just hope I can keep up the good form,” added the American who has yet to lose in eight clay outings this season.Venus entered Madrid on a wildcard as she started her third tournament after seven months out suffering with Sjogren’s Syndrome, an auto-immune disease which causes fatigue and joint soreness.The former world number one struggled past Romania’s Simona Halep in three sets on Saturday, but crumpled against stronger opposition on Monday falling 6-4 6-1 to 12th seed Angelique Kerber of Germany.China’s Li Na, the eighth seed, joined Kerber in the last 16 with a straightforward victory over Spanish wildcard Silvia Soler-Espinosa 6-3 6-1.