Payet has spent the last two months out with an ankle injury following a crude challenge from Everton's James McCarthy back in November.
Slaven Bilic's side lost their mojo as an attacking force in the Frenchman's absence but the 28-year-old showed just how important he is by pulling the strings on his return to the Hammers' starting XI.
The East Londoners were trailing 1-0 at half-time at the Vitality Stadium.
But Payet stepped up in the second half and produced a masterclass, scoring a sublime free-kick and setting up Enner Valencia with some audacious skill before the Ecuadorian sealed the three points with a stunning free-kick of his own.
Payet has proved to be one of the signings of the season after joining Bilic's revolution for £10 million from Marseille in the summer.
"He was absolutely outstanding, different class," Merson said on Sky Sports.
"I mean he scores a worldy free-kick ... and then he does a great bit of skill in the corner, nutmegs someone, picks out Valencia, volley, great goal and then Valencia gets a worldy free-kick.
"He (Payet) plays this ball to Valencia from the halfway line, sidefoot, to the edge of the box and it must cut out five players.
"It's one of the best balls you'll see all season.
"He was absolutely outstanding."
Payet is already idolised by the West Ham faithful.
And the feeling is clearly mutual after the star was seen thanking supporters and bowing to them after the final whistle, beating the badge on his West Ham jacket in the process.
While Valencia's brace sealed a win that pushes Bilic's side up to fifth in the Premier League table after 21 games there was no doubting the star of the show.
Even Cherries boss Eddie Howe admitted his class was the difference on the night.
It leaves Hammers fans dreaming of what might happen with the club poised one point off the Champions League places in this most open of seasons.