Television cameras captured an angry Rosenior confronting members of the Arsenal camp after he believed they had encroached on Chelsea's half of the pitch during preparations. Teams traditionally use separate halves of the field during warm-ups, and the Blues boss admitted the situation disrupted his side's routine.
"In that moment, I didn't think it was right where they were operating. They were affecting my lads' and staff's warm-up," Rosenior explained. "I asked them, maybe not politely, to make sure they stayed in their half. I'm not here to have mind games, it's just what I think is right and respectful."
Rosenior stressed he had no personal issue with Arsenal or manager Mikel Arteta, but insisted that basic football etiquette should be upheld. "I always try to be respectful and I've never asked my coaches to encroach on the opposition's territory," he said.
Arteta downplayed the incident when asked about the claims, saying any misunderstanding would be addressed. "It's his opinion and we respect everybody. If one of our staff members went through that, we apologise and that's it. It's very common in football, especially with goalkeepers and long balls, so there's nothing there to comment," the Arsenal manager said.
The on-field action ultimately went Arsenal's way, with former Chelsea forward Kai Havertz scoring deep into stoppage time to secure a 1-0 win on the night and a 4-2 aggregate triumph, sending the Gunners to Wembley. Rosenior later defended his tactical approach, despite criticism over his cautious setup.
"The noise doesn't surprise me at all," he said. "What people say outside the club makes no difference to my decision-making. In hindsight, we didn't go through, so there are always things you can improve, but it was a very solid performance against a team that is very strong at home. We turned the tide in the second half and the game could easily have gone our way."
The semi-final defeat represents Rosenior's only setback since taking charge of Chelsea in January, having otherwise overseen a strong run that includes a series of Premier League victories and progression to the Champions League last 16.
Attention now turns to Chelsea's upcoming league clash with Wolves, where Rosenior confirmed Cole Palmer and Estêvão Willian are fit to play a full match. Palmer has faced scrutiny over form and fitness after a groin injury earlier in the season, but Rosenior backed the midfielder's progress.
"He's bought in, he's been magnificent. He's maturing and understands the bigger picture with his career," Rosenior said.
Chelsea will, however, be without forward Jamie Gittens, who is facing a spell on the sidelines with a hamstring tear suffered during the win over West Ham. Rosenior admitted the injury could be long-term but declined to give a definitive timeline, describing the setback as a significant loss for the squad.