LAS VEGAS — With Craig Kimbrel and Joe Kelly free agents, the Red Sox have serious interest in David Robertson changing uniforms in baseball’s fiercest rivalry.

“They are heavy on him,’’ a person with knowledge of the World Series champs’ plans said of Robertson.

The Mets continue to talk to Robertson, who is representing himself, and the Yankees have stated often they would like to get two relievers in the offseason via trade or free agency.

Like most free agents, Robertson, who turns 33 in April, is expected to join the team that offers him the most money. How much the role he played in many Yankees’ support staffers receiving a reduced playoff share from what they got in 2017 has affected the team’s desire to bring him back is cloudy but could be a factor.

Reportedly, Kimbrel is seeking the five-year, $86 million deal the Yankees gave Aroldis Chapman before the 2017 season. That might be too rich for the Red Sox who have an interest in Zach Britton. The lefty appeared in 25 games for the Yankees last season after being acquired from the Orioles in late July. He is being shopped by agent Scott Boras as a closer.

Should Robertson, who had a strong 2018 season (3.23 ERA; 91 strikeouts and 46 hits in 69 ²/₃ innings) not return to the Yankees they have engaged free agent right-hander Adam Ottavino and lefty Andrew Miller.

“I don’t know what our competitors are willing to do whether it is a trade or free agency,’’ general manager Brian Cashman said when asked to assess his bullpen picture. “I have legitimate offers out for various trade partners and or free agents. We haven’t agreed do to anything yet.’’