A last-gasp equaliser from Ryan Darmanin dealt a serious setback to Birkirkara's hopes of finishing runners-up to Valletta and thus securing an automatic berth in next season's UEFA Cup.
As happened in recent occasions, the Stripes contrived to be caught at the death by their opponents to miss precious points.
Now Marsaxlokk can overtake them today when they play bottom club Hamrun Spartans. Birkirkara, however, remain second on 31 points, followed by Marsaxlokk on 29 and Sliema on 28.
But while the Stripes have one match to go, Marsaxlokk and Sliema have two more matches to play.
Birkirkara were superior to the Greens in the first half and merited their one-goal cushion - a splendid effort from striker Sylla.
The Stripes took hold of midfield as Floriana operated in swift counter-attacks which, however, never procured any serious trouble to goalkeeper Paris.
In fact, Yantchev and Hartvig were in total command and Thomas Paris and Lino Galea could operate frequently on the flanks giving a lending help to George Mallia and Sean Bajada, with the former easily the best player on the field of play.
Among the Greens, Levniak and Eboh were influential in the heart of the defence while Christian Cassar and Brincat had a rather hard time in midfield.
In the second half Floriana tried hard to save the game as they pressed the Stripes in their own half for long stretches, but they rarely were given the opportunity to have a pot at goal. When they did, Bernard Paris was on hand to keep them at bay.
The Stripes seemed to be a tired lot in the second half and struggled to get upfield as Michael Galea and Davy Sylla were rarely in the match.
It was only left to George Mallia to procure some trouble for the Greens but to little effect.
When everything pointed to a Stripes win, the Greens produced an unexpected, though well merited equaliser.
After a quiet start to the match, Birkirkara had the first chance on 10 minutes but Sylla headed wide from a Tabone freekick.
At the other end, Birkirkara goalie Paris smothered a low shot from Joseph Borg.
The Stripes took the lead on the 24th minute with an excellent goal. Sean Bajada was set on the right by Mallia and from his perfect cross, Sylla first timed beautifully home past a helpless Simon Agius.
Moments later, Bajada was again close with a fine volley but that was what really went on in a rather poor first half.
At the start of the second half, it was all Floriana and in the 49th minute, Sunday Eboh's header went wide.
On 63 minutes, the Greens threatened again when following a cross from Julian Briffa, Mano Micallef's header was saved by Paris.
Floriana tried hard but it was the Stripes, in a counter-attack, who almost scored a second with Bajada's shot passing dangerously across goal.
The Greens roared back in attack and Micallef brought the best out of Paris in the Birkirkara goal. It was, perhaps, the
In the 85th minute, Tabone missed a good chance for Birkirkara hitting weakly from an ideal position after a splendid run by Mifsud Triganza.
In added injury time, the Greens had another chance but Christian Cassar's shot from outside the area went wide.
The Stripes were dealt the cold shower on the stroke of full time. Thomas Paris was shown the red card for a second bookable offence. From Christian Cassar's freekick, Ryan Darmanin seemed to have found the net among a forest of players in the Stripes area.
It meant the Stripes lost two very precious points in their quest to finish in the runner-up position.
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Birkirkara: B. Paris, T. Paris, L. Galea, R. Hartvig, E. Yantchev, P. Fenech (A. Ciantar), G. Mallia, A. Tabone, S. Bajada (M. Anastasi), A. Davy Sylla, M. Galea (JP Mifsud Triganza).
Floriana: S. Agius, J. Briffa (C. Ciantar), Z. Levniac (O. Bugeja), S. Eboh, D. Pisani, C. Cassar, M. Brincat, J. Borg (T. Cilia), Y. Bolasie, M. Micallef, R. Darmanin.
Referee: A. Zammit Asst refs: C. Micallef, J. Spiteri; 4th official: AM Sant
Scorers: AD Sylla, R. Darmanin
Yellow cards: D. Pisani, Z. Levniac, J. Briffa, T. Paris, S. Eboh,
Red card: T. Paris
Player of the match: AD Sylla (Birkirkara)
TMI Top 3: 1. G. Mallia; 2. R. Hartvig; 3. Z. Levniac