PARIS -- Marin Cilic beat Dutch qualifier Igor Sijsling 5-7, 6-1, 6-4 on Monday in the first round of the Paris Masters, his first match since his return from a four-month ban for a positive doping test.
The Croatian served 21 aces and hit 42 winners to only 17 for Sijsling, who double-faulted to give Cilic a 4-3 lead in the deciding set.
"All the players, they know me and they were really happy to see me and they were really happy that this is over for me," Cilic said. "Everybody knows it was like honest mistakes, and it can happen to really anyone. I'm of course definitely against doping, against the players who are cheating, and I would say that there should be some more seminars for the players to be more aware about these things that can happen."
Cilic tested positive for a banned stimulant in May but claimed he ingested it inadvertently though a glucose tablet bought at a pharmacy.
The International Tennis Federation found traces of nikethamide in Cilic's urine sample from a tournament in Munich, where he lost in the second round to fellow Croat Ivan Dodig.
Nikethamide is prohibited in competition but can be used out of competition. Cilic said he had ingested the tablets five days before his match.
When notified in June by the ITF of the positive test, Cilic accepted a provisional suspension and withdrew from a second-round match at Wimbledon, citing a knee injury.
Cilic reached a career-high No. 9 ranking in February 2010. His ranking has dropped to 41st from 12th at Wimbledon.
In September, the ITF hit Cilic with a nine-month ban back-dated to May 1.
"I would definitely say it was the worst time of my life to experience this as a player," Cilic said. "It was extremely difficult situations where people were even calling me a doping player and a cheater."
The governing body's anti-doping tribunal later said Cilic hid behind the excuse of a knee injury to withdraw from his second-round match against Kenny de Schepper at Wimbledon and avoid negative publicity after failing a doping test.
"My lawyers were put under pressure at that time and told me I have to pull out," Cilic said.
Cilic challenged his suspension at the Court of Arbitration for Sport, while the ITF appealed the verdict of its own independent tribunal and requested a two-year ban.
Last Friday, the court reduced Cilic's suspension from nine to four months, allowing him to compete at the Paris Masters.
"I just don't know who I have to believe anymore. I feel like everybody lies, even the institutions," Frenchman Jo-Wilfried Tsonga said. "I feel like even those who are testing us don't always say the truth."
Also Monday, Spaniards Feliciano Lopez and Fernando Verdasco won their first-round matches.
Lopez outlasted Bernard Tomic of Australia 6-4, 6-7 (4), 7-6 (1). Lopez failed to serve out the match at 5-4 in the second set but he recovered in the tiebreaker of the third by winning the last six points.
Verdasco edged Ernests Gulbis of Latvia 7-6 (3), 7-6 (5) despite blowing a 3-0 lead in the second set and converting only one of 11 break points.
Kohlschreiber dismissed Andreas Seppi of Italy 6-3, 3-6, 6-4; Rosol beat Jeremy Chardy of France 6-3, 6-4; Haase defeated Denis Istomin of Uzbekistan 7-6 (8), 6-3; and Giraldo edged French wild card Adrian Mannarino 6-3, 2-6, 6-4.