Ranked 170, Ramkumar came into the tournament after winning both his singles in the Davis Cup tie against Denmark.
Now, the onus is on the pairing of Rohan Bopanna and Divij Sharan (they can still change the nomination) to see the tie through.
Taking full advantage of the Danish player's discomfort on the low bounce grass court, Ramkumar cruised to a 6-3 6-2 win over Christian, ranked as low as 824, in the opening singles of the tie .
Saketh Myneni and Ramkumar Ramanathan brushed aside the French challenge of Hugo Grenier and Alexandre Muller in straight sets, 6-3, 6-2.
The duo on February 6 beat the top seeds from Australia, Luke Saville and John Patrick Smith 6-7, 6-3, 10-6 in the final of the Tata Open Maharashtra at the Balewadi Stadium in Pune.
Ramkumar, who zoomed to a career-best 94, and Bopanna won their second title together on Feb 6 after beating the Australian team of Luke Saville and John-Patrick Smith.
Bopanna and Ramkumar combined as a team on the ATP Tour for the first time at the Adelaide event last month in the run-up to the Australian Open and won the trophy.
The lanky and the fit Ramkumar Ramanathan has made the second round twice (2018, 2019) while Prajnesh Gunneswaran (2020) and Yuki Bhambri (2018) cleared the first round once each.
The team has been selected keeping in mind the playing surface as both India's top-ranked singles player -- Ramkumar and comeback man Yuki -- are comfortable playing on grass courts.
Rohan Bopanna feels Ramkumar Ramanathan's energy and passion allows him to play his best tennis and is looking forward to having another great week in Pune.
It will be Ramkumar's fourth appearance at South Asia's only ATP 250 tournament.
Bopanna's excellent service returns at crucial times and Ramkumar's all-round game tilted the match in their favour.
The Indian combination will now face top seeds Ivan Dodig of Croatia and Brazilian Marcelo Melo in the summit clash of the ATP 250 event.
Bopanna and Ramkumar trounced Benjamin Bonzi and Hugo Nys 6-1 6-3 in the doubles quarterfinals of Adelaide International 1 ATP tournament.
The Indian duo had earlier trounced American Jamie Cerretani and Brazilian Fernando Romboli 6-2 6-1 in the opening round on Tuesday.