Del Potro is one of several players chasing the last three spots for the prestigious end of season tournament in Shanghai, open to only the top eight players in the ATP race, and was in seventh place heading into this week's indoor tournament in Paris.
"I'm trying not to think about it,'' del Potro said. "I always wake up thinking about Shanghai.''
Del Potro next faces eighth-ranked David Nalbandian of Argentina or Nicolas Kiefer. Del Potro beat Nalbandian at the Madrid Masters but Nalbandian won a rematch when they met in the semifinal of last week's Swiss Indoors.
"I'm playing more aggressive now, I'm serving very well,'' del Potro said.
The seventh-seeded Andy Roddick, who is defending sixth place in the ATP race, played Feliciano Lopez later Tuesday.
Del Potro, Roddick and Gilles Simon are looking to gain enough points to hold their ranking in the top eight and reach Shanghai. Simon held eighth place heading into the tournament and played Igor Andreev in the second round on Wednesday.
Also Tuesday, Gael Monfils of France beat Juan Monaco of Argentina 6-4, 6-4 to reach the third round and set up a possible match against top-ranked Rafael Nadal.
Sixteenth-seeded Monfils had never been beyond the second round in two previous appearances at the Bercy indoor arena, while Nadal faces Florent Serra of France in the second round match on Wednesday.
"I wanted to do so well. Juan is a very good player, and he beat me twice already,'' Monfils said. "Thanks to my serve I was able to be more confident.''
Serra beat Guillermo Canas of Argentina 4-6, 7-5, 6-3, while Robin Soderling won his sixth straight match by beating Josselin Ouanna of France 6-3, 6-4 to set up an eighth career meeting against Roger Federer in the second round.
The big serving Swede, who won his third career title at the Lyon Grand Prix on Sunday, broke his French opponent once in each set and saved all four break points he faced in the first round match.
However, Soderling could struggle to continue his winning streak given that he is 0-7 against the 13-time Grand Slam champion Federer, who won his 57th career title by winning the Swiss Indoors for the third straight year on Sunday.
Germany's Philipp Kohlschreiber also advanced to the second round after beating Russia's Mikhail Youzhny 6-1, 6-4, and 2005 runner-up Ivan Ljubicic of Croatia beat Viktor Troicki of Serbia 6-3, 6-4.
Ljubicic next plays 2006 champion Nikolay Davydenko of Russia.
Kohlschreiber had to save eight break points, and next plays fifth-seeded David Ferrer of Spain.
Ferrer is just behind Simon in the ATP race, with James Blake, Stanislas Wawrinka and Australian Open finalist Jo-Wilfried Tsonga all hoping a good showing will help them qualify for the year-end championship.
In later matches Tuesday, No. 3 Novak Djokovic - already qualified with Federer for Shanghai - takes on Dmitry Tursunov.
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