Serena Williams’ husband Alexis Ohanian has splashed out on four giant billboards to mark the tennis star’s return to tournament play in California next week.Ohanian, borrowing a tactic at the centre of Oscar-nominated movie “Three Billboards, Outside Ebbing Missouri”, delighted Williams after the giant adverts appeared on the motorway heading to the desert city of Indian Wells.The first three billboards, which also feature images of the couple’s baby daughter, spell out the message, “Greatest Momma Of All Time”.READ | Alexander Zverev, Juan Martin del Potro untroubled in Mexican Open tennisA fourth billboard reads: “Serena Williams - G.M.O.A.T - Alexis Jr + Sr.”In an Instagram post, Ohanian revealed he had designed and paid for the ads himself.“These just went up alongside I-10 into Palm Springs,” Ohanian wrote. “I wanted to welcome her back to tennis. Designed them myself with some help from Jr,” he added.READ | Laureus Awards: How rival Rafael Nadal made Roger Federer ‘a better player’Williams was bowled over by the gesture. “Literally am crying,” she wrote in a comment under Ohanian’s Instagram post. “This is so sweet. I love you.”Williams, 36, has not played a full WTA tournament since missing most of 2017 due to the birth of her daughter.The 23-time Grand Slam champion played in a Fed Cup game for the United States earlier this month and will return at next week’s BNP Paribas Open at Indian Wells.