|Ricky Martin and the cast of 'Glee' on set|
The 40-year-old pop star is shooting a cameo in the series, and so far he has proved very popular with Lea and the other 'Glee' regulars.
She wrote in a series of posts on twitter: "Back at work! Starting our next episode with my old friend Ricky Martin!
"Having so much fun on set with Ricky! He's seriously the sweetest and such a great fit for our show!"
Lea, 25, also revealed she first worked with Ricky in a stage production of 'Les Miserables' 16 years ago.
In another tweet, she wrote: "I've known Ricky since I'm 8 years old! He was in Les Mis on Broadway with me in 1996! Crazy huh?! (sic)"
'Glee' is renowned for attracting big name stars onto the show, including Gwyneth Paltrow - who played substitute teacher Holly Holliday in multiple episodes - and Britney Spears, who appeared as herself.
Here's some photos of Ricky Martin on set: