"We are defending better and possibly today was our most consistent performance on the ball".
Antoine Griezmann scored one and assisted one as Atletico Madrid moved within two points of Sevilla.
According to The Sun, Atletico fear Griezmann is heading out of the Vicente Calderon at the end of this season and have already begun the search for his replacement.
It capped a miserable week for Sevilla after being knocked out of the Champions League by Leicester, who will face Atletico in the quarter-finals.
Trailing Sevilla by five points at the start of the day, Atletico knew a win would help reel in their opponents who occupied the last automatic Champions League qualifying berth in the Spanish top-flight.
The goal was Griezmann's fifth in a four-round scoring run and took his tally to 14 in the competition and 22 overall this season.
Koke's 77th minute strike all but assured the win for Atletico before Joaquin Correa pulled one back for Sevilla, but it was Griezmann's strike that determined proceedings.
"Logically the league is now a long way off", said Sampaoli.
Atletico lost defender Sime Vrsaljko to a left-knee injury in the opening minutes of the match.
Iago Aspas scored in the 74th as Celta Vigo won a regional derby at Deportivo La Coruna.
The France worldwide is also wanted by a number of other top clubs ahead of the summer, but latest speculation suggests United are leading the queue.