"Time to swooooooonnnnn. Yup! He's backkkkkkkkkkkk. That southern gentleman that stole all of our hearts- @harryconnickjr . There will never be another Leo.❤," Debra Messing, who plays Grace Adler, wrote on Instagram on Wednesday. Connick Jr. played Leo Markus, a doctor who went on to marry Adler (Messing).
Also ecstatic about working with the actor again was Megan Mullally, who shared a selfie of the two on Instagram.
"This one. SUCH A GREAT GUY.So fun to be around. We love you @harryconnickjr welcome back! #willandgrace @nbcwillandgrace," she wrote. Mullally also shared a hilarious video of co-star Sean Hayes sitting on Connick Jr.'s lap while playing the piano.
The Will & Grace revival -- which has already been renewed for a second season -- sees the original four cast members, Messing, Hayes, Mullally and Eric McCormack, reprising their characters after more than 11 years.
ET spoke with the cast earlier this month, where they dished on what to expect, how excited they were to be working together again and how they plan to address the series finale, which featured a 20-year time jump.