Interim Manchester United manager Ralf Rangnick has revealed why Edinson Cavani has not been named in the matchday squad for the Red Devils against Southampton.The German tactician explained that the Uruguayan superstar suffered a groin injury in the final training session on Friday. Despite receiving treatment overnight, he ruled himself out on the morning of the game.Cavani's absence meant Cristiano Ronaldo started the game up front for the 20-time champions of England having found himself on the bench against Burnley in midweek. Rangnick told MUTV regarding the absence of Cavani:“I decided to start with Cristiano today, Edi had to pull out after training last night, he has groin problems, he had treatment the whole night and whole morning. But in the end, he said he’s just not available. It would be good [if Ronaldo scored] but no matter who scored for us, it's important to win the game."BBC Sport@BBCSportManchester United interim boss Ralf Rangnick says it is 'obvious' the club needs to buy a striker in the summer.#BBCFootball5:24 AM · Feb 12, 202240533Manchester United interim boss Ralf Rangnick says it is 'obvious' the club needs to buy a striker in the summer.#BBCFootballWith Cavani out of contention, highly-rated midfielder Hannibal Mejbri found himself on the bench for Manchester United for the first time in the Premier League this season. Alex Telles also made the bench with Nemanja Matic ruled out with a shin injury.Cavani's days at Manchester United look numbered The next summer will be a crucial one for Manchester United as the club have several big decisions to make. The Red Devils need to sort out their managerial situation with Rangnick set to take up a consultancy role.Erik ten Hag, Maurico Pochettino and Brendan Rodgers are all believed to be in the running for the United job while Luis Enrique is also believed to an option. Rangnick was also thought to be keen to land the job permanently but he has not made the desired impact at Old Trafford.Meanwhile, Edinson Cavani has been tipped to leave the Red Devils this summer with his contract set to expire as per transfer expert Fabrizio Romano.Fabrizio Romano@FabrizioRomanoEdinson Cavani is expected to leave Man United in June as free agent - his priority will be to try an experience in La Liga. Spain could be his next destination, but Cavani will only decide in the coming months. #MUFC River Plate, not even an option for Cavani's future.3:34 AM · Feb 12, 2022175161469Edinson Cavani is expected to leave Man United in June as free agent - his priority will be to try an experience in La Liga. Spain could be his next destination, but Cavani will only decide in the coming months. 🔴🇺🇾 #MUFC River Plate, not even an option for Cavani's future. https://t.co/wjBMJmwPrHRangnick himself confirmed in Friday’s pre-match press conference that the club will be looking for a new option up front in the summer transfer market.