(Recasts, add results)
By Gregory Blachier
MONTE CARLO, April 16 (Reuters) - Novak Djokovic will be hoping his gamble to play in the Monte Carlo Masters does not leave his claycourt season going bust after he decided to test his injured ankle in the glamorous principality.
Djokovic's participation provided a boost to the organisers, who now have three of tennis' Big Four playing in the event, with only Roger Federer opting to stay away from Monaco.
While Djokovic, who badly sprained his ankle 10 days ago, eight-times champion Rafa Nadal and U.S. Open holder Andy Murray will begin their seasons on red dirt on Wednesday, Juan Martin Del Potro moved into the third round with tricky 1-6 6-4 6-3 win over Alexandr Dolgopolov on Tuesday.
The towering Argentine, who had not played on clay since last year's French Open, struggled to find his feet in the opening set as Dolgopolov dictated play and produced some fine dropshots.
As the sun set over the Mediterranean, Del Potro started to play deeper and took advantage the Ukrainian's wayward shots to wrap up the next two sets for victory.
"It was really tough to start playing on clay against him. You always try to play long rallies to feel the clay, to settle your play," fifth seed Del Potro said.
"He plays fast, he comes to the net often ... After one hour and a half, I felt better," added the world number six, who had not planned to come to Monte Carlo but was given a wildcard.
French number one Jo-Wilfried Tsonga also made it to the last 16 thanks to an authoritative 7-6 6-2 victory over Nikolay Davydenko.
Sixth-seed Tsonga trailed 0-2 in the first set but quickly regrouped and whipped up the roaring crowd by charging to victory.
World number nine Gasquet completed a successful day for the French favourites as he showed no ill effects of the ankle injury that kept him out of the Davis Cup quarter-finals and completed a 6-1 3-6 6-1 win over countryman Benoit Paire.
Serbia's Janko Tipsarevic was the only top-10 player to suffer an early exit with a 7-6 6-1 defeat by Bulgarian Grigor Dimitrov.
Nadal will launch his bid for a ninth consecutive Monte Carlo title against little-known Australian Marinko Matosevic, while 2012 runner-up Djokovic faces a tricky outing against Russian Mikhail Youzhny. (Reporting by Gregory Blachier; Editing by Pritha Sarkar)