Sevilla failed to close the eight-point gap to leaders Real Madrid, who have a game in hand, and now only hold a two-point leader over Atletico in the race for the final automatic Champions League qualification berth.
In the wake of their elimination from Europe's premier club competition at the hands of Leicester City in midweek, the loss at the Vicente Calderon was a bitter blow for Sampaoli, who sees holding off Diego Simeone's side as their new objective.
"It is the first defeat after nine [sic, seven] games and logically the chance of winning LaLiga is moving away," he told a post-match media conference.
"Now we have to look at the possibility of qualifying automatically for the Champions League.
"It is normal that when you do not get what you want – a win – there is frustration and bitterness [in the dressing room].
"We have taken a very hard blow and we must try to find the solutions and the authentic Sevilla."