After the wife of reliever Joe Kelly offered her husband's uniform number to help lure Shohei Ohtani to the Los Angeles Dodgers, the baseball superstar has responded by giving her a Porsche.

The Dodgers shared a video showing Kelly's wife, Ashley, who had launched what she dubbed her #Ohtake17 campaign in hopes that the free agent from Japan would sign with the team. She showed him all the No.17 garb her family had that could be repurposed for Ohtani and his family and offered to rename the couple's baby, Kai, to ShoKai.

In the video posted this weekend, she opens the front door to reveal a silver sports car parked in front of the house.

"It's yours, from Shohei," a man off camera says in the video to the stunned woman. "He wanted to gift you a Porsche."

Ohtani received a record $700 million (A1.03 billion), 10-year contract this month to make a 30-mile move up Interstate 5 to the Dodgers. He had worn No. 17 with the Los Angeles Angels.

Kelly, who wore No.17 with the Dodgers from 2019-21 and again last season, is switching to No. 99 after finalising his own $8 million ($A11.7m), one-year contract.

"I wasn't going to give it up to just anybody," Kelly said after Ohtani was announced as his new teammate. "If Shohei keeps performing, he'll be a future Hall of Famer and I'll be able to have my number retired. That's the closest I'll get to the Hall of Fame."

Asked what Ohtani was giving him in return, Kelly said, "Oh, there's a list, but no comment."