In the morning the 22-year-old, ranked 15th in the world after a long spell out through illness last year and an injury at the start of this season, weathered a baseline battle to beat 22-year-old Czech Iveta Benesova 7-5, 4-6, 6-1.
Henin-Hardenne was frequently taken to deuce by the Czech left-hander who put up a spirited fight from the start but floundered in the final set of the first round match.
Just hours later the Belgian was challenged by Russian teenager Maria Kirilenko but recovered from a disastrous start to win 2-6, 6-1, 6-3.
Henin-Hardenne described the day as a slog but said her hard-fought
"It gives me confidence to see that I could play six sets," she said. "I am happy the day is done."
Henin-Hardenne, who won the French Open in 2003, said she was not concentrating on the Grand Slam but felt her game was improving.
The Belgian has claimed two successive clay court titles, including the Warsaw tournament on Sunday, and has now won two of the three events she has played since returning to the circuit in March.