It's no secret that Birmingham City wanted the winger and other Championship clubs were keeping close tabs on developments.
It's that sort of situation that can spark a bidding war and Brighton could have used the interest in Sarmiento to their advantage.
But the Ecuadorian winger sat down with Albion officials and made his feelings clear - he wanted the move to Middlesbrough.
That, looking back on the winter window, is why Boro were able to resume negotiations with the Seagulls after it looked like they'd had to admit defeat in the pursuit of the wideman.
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Boro had other wide attacking options in January but Sarmiento was the one Hellberg really wanted.
Boro's head coach has made no secret of the fact Roberto De Zerbi is one of his managerial inspirations, and it was when the Italian was in charge of Brighton that the Swede first watched Sarmiento.
It was during De Zerbi's time in charge that Sarmiento played most of his football for Brighton. And the winger sees a lot of similarities between Hellberg and De Zerbi, described by Liverpool's boss Arne Slot earlier this year as "one of the best managers in the world".
"100 per cent," Sarmiento tells the Northern Echo.
"The way he wants his No.10s to get on the ball as much as possible and attract players and play in between pockets and lines.
"For me, it's very important because I can get on the half turn and drive at players."
The way Hellberg wants to play the game is one of the reasons why Boro was the only move Sarmiento wanted in January.
"As you guys saw and as was reported in the media, there were other teams interested but Middlesbrough was the place I wanted to go," he says.
"I spoke to Brighton and made that very clear. The playing style suits me. I like to play as a 10 or sometimes come off the wing.
"I'm enjoying my football in this position. It works well. Kim has given me the confidence to do what I do well, and as a player that's all you want.
"I've had some loan spells at Championship clubs and I played against Middlesbrough. They've always played good, attractive football. It was always appealing to me.
"I spoke to the boss, he laid it out for me and it felt like the right place. As a player you want to push for big things and Middlesbrough are certainly doing that. We want to get promoted, that's the big objective."
And, despite the frustrations of the home defeat to Charlton and draw with Bristol City, Boro remain very well placed ahead of tomorrow's lunchtime game at Blackburn.
Sarmiento will be hoping to keep his place in the side after making what was just his second start for Boro against the Robins last week.
Hellberg always knew Sarmiento was unlikely to be overnight hit, however, simply because the forward had played next to no football in the first half of the season while on loan with Cremonese in Italy.
But since making his debut in the home win over Norwich at the end of January, Sarmiento has played some part in every Boro game.
Sarmiento joined Boro on an initial loan in January, but the deal will be made permanent this summer, and after a string of temporary moves the winger wants to make Teesside home.
"Yeah, 100 per cent, that's my aim here, to find somewhere I call home and this definitely feels like the place," he says.
"I'm enjoying every bit of it. The lads are great, the staff are great."