Boston Celtics center Kristaps Porzingis is expected to sit out Games 1 and 2 of next week’s Eastern Conference Finals, but there is optimism he will be able to return at some point in the series — barring any setbacks, sources told ESPN on Friday.

Porzingis is making progress in his recovery from a right calf strain, increasing his activity on the court for an expected return in the conference finals, but he still needs more time to return to action, sources said.

The Celtics team awaits the winner of the New York Knicks-Indiana Pacers match in the semi-finals. The Knicks lead 3-2 entering Game 6 on Friday (8:30 p.m. ET, ESPN).

Porzingis — who has been sidelined since suffering an injury in Game 5 of the Celtics’ first-round series against the Miami Heat on April 30 — missed the entirety of Boston’s five-game conference semifinal series win over Cleveland.

He is likely to miss the opening two games of the Eastern Conference Finals scheduled for Tuesday and Thursday in Boston.

At 7 feet 3 inches tall, the return of Porzingis — who averaged 20 points and 7.2 rebounds in the regular season — is crucial to the Celtics’ eventual chances of winning a championship.

Al Horford, 37, started in Porzingis’ place. Horford had 22 points, 15 rebounds, 5 assists and 3 blocks in the win over Cleveland on Wednesday.

Porzingis arrived in Boston via a three-team trade with Washington and Memphis.