Defending champion Nikolay Davydenko continued his comeback from a serious injury by taking just 58 minutes to cruise through to the third round of the German Open in Hamburg on Tuesday.
Still rebuilding after three months out earlier this year, Davydenko produced a dominant performance on serve to overwhelm Frenchman Florent Serra 6-3 6-1.
Seeds Tommy Robredo and Gilles Simon were both casualties however. Robredo, seeded 11th, lost 7-6 5-7 6-1 to Potito Starace, while ninth seed Simon went down 6-4 3-6 7-5 to Finland's Jarkko Nieminen.
Florian Mayer gave the home crowd something to cheer as he made it safely through to the third round with a 4-6 7-6 (7-2) 6-3 win over another seed, 15th seed Aleksandr Dolgopolov of the Ukraine.
Other first round action included victory for Julian Reister over Daniel Brands in the battle of German wild cards, with Argentinian pair Juan Ignacio Chela and Eduardo Schwank also advanced.
Meanwhile, Serbia's Janko Tipsarevic was the biggest casualty on the second day of the Atlanta Tennis Championships.
Tipsarevic was seeded fifth for the hard-court tournament but fell meekly in the first round as South Africa's Kevin Anderson posted a comfortable 6-3 7-5 triumph.
Taylor Dent prevailed in an all-American battle with James Blake, the world No.94 needing almost two hours to secure a 6-3 3-6 6-4 triumph.
Seventh-seeded Belgian Xavier Malisse also progressed into round two as he saw off the challenge of American qualifier Ryan Sweeting 7-6 (7-1) 6-3.
Malisse was runner-up in Atlanta to Andy Roddick in the last staging of the tournament in 2001 and will meet Illya Marchenko in the next round.
Hometown favourite Robby Ginepri booked a second-meeting with fellow American Mardy Fish courtesy of a 7-6 (7-4) 6-2 triumph over Australian qualifier Nick Lindahl, while there were also wins for Donald Young, Lukas Lacko and Gilles Muller.
Muller will meet second seed John Isner in the next round while Lacko faces third-seeded Australian Lleyton Hewitt.