The flashpoint came at Riera's pre-match press conference ahead of Saturday's Bundesliga home fixture against Hamburger SV, after Bild reported on Thursday that the Spanish coach had been unhappy with Burkardt's body fat percentage — and had communicated his concerns through assistant coach Jan Fießer rather than speaking directly to the 25-year-old forward.
According to the report, Burkardt was irritated both by the critique itself and by the manner in which it was delivered, leading him to contact his agent, who raised the matter with sporting director Markus Krösche. Krösche then spoke to Riera, after which the coach reportedly confronted Burkardt in passing.
Riera denied the framing of events in explosive terms.
"That is total bulls*t. This is not a bar or a circus. It's a very serious, professional football club. You journalists speak to agents — I don't know what goes on there. But you have a poisoned environment. The information you give — at least give the right information. Not lies."
He insisted the relationship with his squad is intact and that his decision to bench Burkardt recently — the forward sat on the bench for 88 minutes in the 1-1 draw at Augsburg — was a tactical choice that produced the reaction he was looking for.
"When he was on the bench, the next day he was training like crazy. I said to him: this is what I wanted. A reaction. Jonny showed a fantastic reaction. We have no problems or issues in this building. We have a fantastic relationship with each other."
He rounded off with a direct message to those reporting on the situation.
"Writing things is your job, but I will not accept lies. I am not a puppet. I am a coach and I demand respect. The fans deserve to hear the truth."
Riera did, however, acknowledge that an incident with Burkardt had occurred — though he put the episode firmly in the past and characterised it as resolved. The admission that anything happened at all contradicts the totality of his denial, and the atmosphere around the club remains tense ahead of the end of a difficult Bundesliga season.
Eintracht Frankfurt sit seventh, targeting a European qualification spot with three games remaining.