The S.League champions committed the offence in their away 1-0 victory against Harimau Muda, which has resulted in the latter being awarded a 3-0 win
The defending champions were found to have committed the offence on July 3 in their game against Harimau Muda away at the Pasir Gudang Stadium, which they won 1-0.
The Football Association of Singapore (FAS) has released a short statement about the issue, which includes the decision to overturn the result and award a 3-0 win in favour of Harimau Muda.
The player in question is Ruzaini Zainal, who joined the Stags in the mid-season transfer window from Warriors FC.
"After a thorough investigation, it was established that Tampines Rovers has fielded an ineligible player," the FAS statement read.
"In his time at Warriors FC, he [Ruzaini] had accumulated a total of three yellow cards to his name.
"Ruzaini played his first S.League match for Tampines against Warriors FC, on June 28. He picked up his fourth yellow card of the season, which meant an automatic one-match suspension in the following match against Harimau Muda, which he played in.
"In line with S.League’s rules and regulations, we have decided to overturn Tampines Rovers' 1-0 win over Harimau Muda and award Harimau Muda with a 3-0 win. Tampines Rovers FC and Harimau Muda have both been informed of the League’s decision, which will be effective immediately."
This is the second such incident to happen in the S.League this season. Earlier this year, it was found that the Courts Young Lions had fielded ineligible players in four matches, as some of them had not received the proper clearance to be released from National Service duties. The team’s opponents in those games were all awarded 3-0 wins as well.