Davis Cuppers Yuki Bhambri and N Sriram Balaji advanced to the second round of the $75,000 Karshi Challenger but other Indians in the fray stumbled at the first round itself, here.
Yuki ended the campaign of compatriot Prajnesh Gunneswaran with a 6-4 6-2 win in an all-Indian first round contest at the hard-court event.
Balaji, who had made an impressive Davis Cup debut against Uzbekistan, knocked out local wild card entrant Farrukh Dustov 6-3 6-1.
However, Ramkumar, who recently made his first ever Challenger level final in Tallahassee, went down fighting 4-6 4-6 against Italy's Cem Ilkel.
Ramkumar is ranked 216 while his opponent is placed 326 in the ATP singles ranking chart.
National hard court champion Vishnu Vardhan had bowed out of the tournament on Monday with a 3-6 5-7 defeat against Ukraine's Vladvyslav Manafov.