Taylor Swift's stealthy entrance at Dakota Johnson's birthday party

Taylor Swift helped Dakota Johnson celebrate her 37th birthday at the SNL after-party this weekend, and the whole thing involved a stealthy entrance, greasy food and a room full of A-list friends.

Page Six reports that Swift secretly snuck into the fancy fete at L'Avenue at Saks after crashing Johnson's SNL monologue earlier in the evening.

"Taylor came, but didn't use the L'Avenue entrance," a source told Page Six. The singer was only there for "about an hour."

Swift was joined by pals Cara Delevingne and Ashley Avignone, and the group was spotted noshing on French fries at a table right next to Johnson's setup.

"Everyone was crowding around for Dakota's birthday," the source added. "The vibes were great."

A second source told Page Six that the SNL cast helped mark the occasion with oversized silver balloons spelling out Johnson's name.

Also at the party: musical guest Turnstile, SNL cast member Michael Che, Nathan Fielder, Stephen Spielberg, Gabby Windey, Robby Hoffman, John Wilson, Shane Gillis, Kelli Finglass, Shai Fruchter and Dom Dolla, who was spotted chatting and mingling with guests after his show for 40,000 fans in Queens.

Earlier in the evening, Johnson returned to Studio 8H for her third SNL hosting stint, with Swift making a surprise appearance during the monologue. The singer presented Johnson with a birthday cake at the end of the show.

Page Six also exclusively reported that Johnson continued her birthday celebrations Sunday evening with a festive dinner at Via Carota in the West Village, joined by Jennifer Lawrence and her husband, Cooke Maroney. Swift wasn't spotted at that dinner.

• birthday party
• Dakota Johnson
• L'Avenue at Saks
• Page Six
• SNL
• Taylor Swift