Lohan and Spears
Stephen Shugerman/Getty; Flynet
Britney Spears's third live show in less than a week drew a large crowd that included Lindsay Lohan on Thursday.
Lohan was spotted in the balcony at the House of Blues in West Hollywood, where The Hills'
Whitney Port also braved the tight security (one fan even put his arm in a cast to smuggle in a recording device – only to be busted once inside).
Dressed in the same miniskirt and bikini top costume she'd worn at her shows in San Diego
, Spears performed the same medley of past hits she'd lip-synched at the previous concerts.
Lohan, like Spears a recent rehab alum, and the pop star go way back, at least by Hollywood standards: They hit the L.A. nightclub circuit along with Paris Hilton shortly after Spears filed for divorce
from Kevin Federline in November.
Latin R&B singer Frankie J, who opened for Spears in Anaheim and Los Angeles, tells PEOPLE that despite the mixed reviews for her short performances, she accomplished what she set out to do.
"She left everybody still wanting more, which is the trick," he says. "You want to leave the fans with that anxiety. She definitely did that."
He adds: "I think she just wanted to make a statement and say: Look, I'm still here. I'm not going away."
Spears is scheduled to perform another show at the House of Blues Las Vegas inside Mandalay Bay on Sunday.
Reporting by LISA INGRASSIA and JESSICA HERNDON