Su, who turns 55 today, is accused of offering €2,000 (S$3,026) to Singapore Table Tennis Association (STTA) technical director Loy Soo Han, so as to influence an STTA investigation into her son.
At the Criminal Mentions Court, Su had said she would plead guilty.
However, when her case was mentioned again later in the day, she disputed an important fact relating to her charge, read by Deputy Public Prosecutor Sanjiv Vaswani.
DPP Sanjiv's statement of facts said that Su "took out an envelope containing €2,000 from her bag and offered this to Loy".
"When Loy realised what Su's intentions were, he immediately told Su to leave his office, locking himself in. He then telephoned STTA chief executive Wong Hui Leng and reported the incident to her, before subsequently filing a police report."
But Su said through a court interpreter that she had gone to Mr Loy's office with the intention of asking him out for lunch. She added that she took out the envelope (with the money), but put it back in her bag without saying a word.
While Su maintained that she still wanted to plead guilty, District Judge Adam Nakhoda said this was an important fact of her charge and rejected her guilty plea.
A pretrial conference date has been set for next Thursday.
Su, looking solemn in black long-sleeved top and pants, arrived at the State Courts alone. She was joined in the building by Mr Bernard Tan, a friend of Mr Li.
The duo declined to comment when asked about their next course of action, or if they would hire a lawyer.
Su allegedly tried to bribe Mr Loy after her son Li was hauled before an STTA disciplinary committee last month for violating house rules.
A former world junior singles champion, Mr Li, 28, had let a female friend spend a night at the STTA hostel, located at its Toa Payoh headquarters.
Mr Li, a Hubei native, was eventually sacked. The STTA said its decision took into account his previous disciplinary issues.
In 2013, former STTA president Choo Wee Khiang, who is also a former Member of Parliament, was cleared of misappropriating funds to pay an assistant coach.
The prosecution appealed, but the decision was upheld by the High Court a year later.
Former STTA high-performance manager Koh Li Ping was also acquitted of helping Mr Choo commit the alleged offence.
In a press statement, the Corrupt Practices Investigation Bureau said: "Singapore adopts a zero-tolerance approach towards corruption. The Corrupt Practices Investigation Bureau takes a serious view of any corrupt practices and will not hesitate to take action against any party involved in such acts."
If found guilty, Su faces a fine of up to $100,000 or up to five years in jail, or both.
