Christian Benteke opened his Crystal Palace account to earn his side a first win of the Premier League campaign, while at the same time ending Middlesbrough's own unbeaten start.
The summer signing from Liverpool opened the scoring at the end of a Wilfried Zaha cross, and it was the English winger who eventually settled the contest after Daniel Ayala levelled up.
James Ward had to be alert to deny Alvaro Negredo's acrobatic attempt earlier in the match, following a near miss from Gaston Ramirez who was only denied by Steven Mandanda, in for Wayne Hennessey this afternoon.
Boro had two penalty appeals turned down across the 90 minutes, as Scott Dann appeared to handle a cross and Zaza got too close to George Friend in added time, but both shouts were rejected.
Benteke's towering header opened the scoring in the North-East, but Ayala levelled up the contest shortly before the interval to keep Boro on track for some club history, as they looked to make it four games unbeaten to kick off a campaign for the first time since 1976.
Aitor Karanka's men, so strong defensively in the second tier, struggled to keep out their opponents, though, and Zaha was able to edge his side back in front two minutes after the restart.
James McCarthur prodded the ball through for his teammate to do the rest and, despite Boro's pressing, there was to be no way through for a second time as the Eagles held firm.
Palace move into the top half of the table with their first win of the campaign, a point behind their ninth-placed opponents.
