Free-agent center Nene "is back at square one" in free agency after the Houston Rockets had to pull back an accepted four-year, $15 million deal due to an age rule, a source told The Undefeated.

Nene and the Rockets agreed to the deal Friday. Houston, however, was not permitted to offer a four-year contract because of the Over 38 rule.

The fourth season of the initially proposed contract would have been during Nene's 38th birthday. The Rockets have countered with a three-year, $10 million offer to Nene that he has not accepted, a source said.

Nene is now back in the free-agent pool and open to talking to other NBA teams, a source said. Houston, however, is optimistic it will work out a contract with the 34-year-old before he is eligible to re-sign.

One Rockets source said it's imperative that Nene is re-signed to play alongside All-Stars James Harden and newcomer Chris Paul.

Nene averaged 9.1 points and 4.2 rebounds primarily as a reserve in his first season with the Rockets last season. The Brazilian suffered a season-ending tear in a muscle in his left thigh during Game 4 of the Western Conference finals against the San Antonio Spurs last season.

The 15-year veteran averaged 10 points and 4.7 rebounds in nine postseason games last campaign.