Ex-Liverpool winger Riera is currently in charge at the Slovenian club and has won 55 per cent of his matches at the helm since arriving in July 2024.
The Spaniard oversaw a 2-0 victory against League of Ireland champions-in-waiting Shamrock Rovers on Thursday night but the action on the pitch took a back seat due to a feud off it.
Ex-Liverpool man in hot water over rival manager comments
Shamrock Rovers triumphed in that particular two-legged affair, before which Riera had bullishly predicted his team to win.
Having overturned a first leg deficit against the Slovenian side, Rovers coach Bradley described Riera's pre-match comments as 'complete arrogance', accusing the former Manchester City winger of a 'lack of respect.'
This season, in the league phase of the Europa Conference League, the two sides were drawn to play each other again.
On this occasion, Riera's Celje won 2-0, after which the Spaniard critiqued Bradley's coaching career in what has been described by Irish media as a personal attack on the Rovers manager.
Riera suggested Bradley had spent the past nine years coaching in the League of Ireland because there was not sufficient interest in his coaching services from teams in more prestigious leagues.
"I can say that Shamrock [Rovers] didn't surprise me at all," Riera said at full-time. "We are far away of the level [from Shamrock Rovers]. Playing in a really average second half we could even score more goals. We let them have some chances but in general, we show in 90 minutes that we have a better level than them. And so we won.
"What happened on the green has to stay on the green, right? How you respect me, I respect you. So, I will not be bad to you, but if you disrespect me in this way," Riera added, referencing his decision not to shake hands with Bradley at full-time.
"There's no one coming from abroad. I think this means something.""If he did his homework, he wouldn't be talking like that. It's quite clear the last few years what my number one priority was."There's no love lost between Stephen Bradley and Albert Riera....#LOI pic.twitter.com/l5Hp3XJXBBOctober 24, 2025
"Personally, I will not say any word because I don't know him and I don't want to know him."
"We didn't even have one coffee. And anyway, I will not give him the chance to have a coffee with me because after one year, still [he] didn't apologise, and this I will not accept.
"He's someone that is many, many years here. I think nine years already here. Even winning here in this country and you stay in this country still. No [club] coming anyone from abroad. I think this means some things."
Bradley has since denied the suggestion he has remained in Ireland due to his coaching credentials, or lack thereof, citing family matters as a key reason for his longevity on home turf.
Irish outlet Extra.ie came to Bradley's defence, writing: "Its clear to see that Riera isnt clued up on why Bradley has remained at Rovers all these years, especially recently, as his son Josh was receiving treatment for leukaemia. Bradley has reportedly received a lot of interest from over in England in recent years, but has stayed at home to support his family through a testing time."
In a post-match interview with RTE, Bradley said of Riera: "The man has no class whatsoever in any aspect. I think its quite clear to see that with him.
"So yeah, theres no point in pretending to like each other. Last year, he showed us no respect, and afterwards he was talking and saying theyd come here and beat us, blah, blah, blah. We beat them. But how hes spoken sums him up really.
"I think if he did his homework, he wouldn't be talking like that. I think its quite clear, the last few years, what my number one priority was."
Riera's Celje are third in the Conference League standings and sit top of the table in Slovenia with 10 wins and two draws from a dozen matches this season.
