By Alexis L. Loinaz
Updated October 31, 2016 03:13 PM
Presley Ann/Patrick McMullan via Getty (2)

They may no longer be a couple, but Liev Schreiber still has a big fan in Naomi Watts.

A month after the two announced their split, the actress attended the opening night of Schreiber’s eagerly anticipated new Broadway play Les Liaisons Dangereuses on Sunday.

Watts, 48, kept her look understated and monochromatic for the evening, walking the red carpet in a black skirt and coat and a patterned white shirt.

Schreiber, 49, took to Instagram shortly before the show, flashing a thumbs-up along with the caption “Happy Opening Night to this extraordinary company! @liaisonsbway #lesliaisonsdangereuses.”

The revival of the celebrated period play about upper-crust deception and intrigue — and based on Pierre Choderlos de Laclos’ famed 1782 novel — has so far earned generally favorable reviews, with Schreiber appearing opposite Albert Nobbs‘ Janet McTeer.

Schreiber and Watts jointly announced on Sept. 26 that they were splitting after 11 years together, saying in a statement, “It is with great love, respect, and friendship in our hearts that we look forward to raising our children together and exploring this new phase of our relationship.”

They’ve made good on that commitment. Since the split, the two have sent warm birthday greetings to each other, and were spotted chatting outside her apartment building in Manhattan.

They were also seen taking their two sons, Alexander “Sasha” Pete, 8, and Samuel Kai, 7, to lunch in New York City in mid-October.

On Sunday, they each posted fun Instagram photos of their sons decked out in ghoulish Halloween getups.

“Happy Halloween!! #boo,” Watts captioned her spooky snap (which featured her dressed up as a blood-splattered ballerina), while Schreiber dubbed his pic “My gorgeous ghouls.”