Eighth-ranked Roberto Bautista Agut of Spain was the only seed to fall on the second day of the Chennai Open.
The world No 58 was stunned by Russian qualifier Alexander Kudryavtsev 6-4 3-6 6-3, who will now face Aljaz Bedene of Slovenia, who fought off a spirited challenge from Swiss qualifer Henri Laaksonen.
Seventh seed Edouard Roger-Vasselin of France qualified for a second-round clash against Jiri Vesely of the Czech Republic with a 6-1 6-3 win over Spaniard Albert Ramos.
"It was very hot and humid out there and that made it tough for me as the match went on," the 30-year-old Frenchman said. "I am just glad it did not go into a third set."
Indian wildcard Yuki Bhambri delighted home fans with a 6-4 6-3 win over Pablo Carreno Busta, who had been voted the ATP's most improved player for 2013 after jumping 650 places in the rankings.
The Spaniard, ranked 64 against Bhambri's 195, was unable to settle down against the Indian's aggressive play and went out in his first appearance in the tournament.
Chennai-based Ramkumar Ramanathan, playing his maiden ATP Tour match, gave local fans another reason to celebrate when he came from behind to stun better-known compatriot and India's top player Somdev Devvarman 4-6 6-3 6-4.
The top four seeds - Stanislas Wawrinka, Mikhail Youzhny, Fognini and Benoit Paire - will be seen in action from Wednesday after being handed first-round byes.