Middlesbrough boss Kim Hellberg said "it breaks my heart" to see his side lose in the Championship play-off semi-final to Southampton amid the latter's alleged spying incident.

The Saints had been accused of sending a spy to their opponents' training session ahead of a goalless first leg, and they won 2-1 at St. Mary's Stadium on Tuesday to reach the play-off final.

Riley McGree gave Boro the lead just five minutes into the second leg, but Ross Stewart equalised ahead of half-time, before Shea Charles scored the winner in extra-time.

Boro have now lost their last three Championship play-off semi-final ties (also in 2018 and 2023), while their five-game unbeaten run against Southampton also came to an end (W2 D3).

Hellberg believes Boro's defeat weighed even heavier due to Southampton's alleged spying, with the Boro boss venting his frustration.

"I worked 15 years as a coach, trying to get to the Premier League. That's my dream for 15 years," he said in his post-match press conference.

The thoughts of Kim Hellberg. pic.twitter.com/5oGSmJKqsn

— Middlesbrough FC (@Boro) May 12, 2026

"I know there are clubs with bigger resources or parachute payments that can spend more money. There are teams that have bigger squads than us, teams that have more money to spend.

"If we wouldn't have caught that man they sent up on a five-hour drive, you would sit there and say, well done, maybe, in the tactical aspect of the game and I would go home and feel like I had failed in that aspect I had to help my players with.

"When that is taken away from you in that way, when someone decides: 'No, we're not going to watch every game. We'll send someone instead and film the session and see everything and hope we don't get caught'.

"It breaks my heart in terms of all those things I believe in. That's the thing.

"I don't care if there are other rules in different countries. This is England where football is the biggest thing.

"That's my feelings about it. I think it's disgraceful. It makes me very sad."