Following the 2010 European Championship that was held in Zagreb, the representatives of local club and record 7 times LEN Euroleague champions HAVK Mladost approached Udovičić about joining their club. Numerous clubs also approached Udovičić in a desire to sign him, including Partizan Belgrade, Olympiacos, Jug, Savona, Spartak, Jadran, Budva and Vojvodina. On 16 September 2010, he was unveiled as the Mladost new acquisition on a one-year contract. With the number 7 cap, according to unofficial information, he would earn about 120.000 euros. On his press conference, he stated: "Arrival in Mladost is a major challenge, this is the most successful European club that has a huge rating in the European water polo. I'm glad we agreed on the conditions and I hope to be fit as soon as possible so I can give the club what is expected of me." Vanja was named "Athlete of the Year" by the LEN magazine in November. He came in first place with 59% of votes in front of Damir Burić with 29% and Stefano Tempesti 12%. The three of them all together won the LEN Euroleague with Pro Recco in 2010. He got the first trophy with Mladost in December 2010 winning the National Cup of Croatia. Mladost played against Primorje EB in the final defeating them 10–7. Udovičić was the top scorer in his team with 3 goals. Vanja was offered a new contract in May 2011. which he didn't sign immediately. Beside the Zagrebs club offer, there were two other serious contenders for his engagement. Italians first division teams CN Posillipo and Savona. In August 2011. it was confirmed that Udovičić would stay and play at least one more season for Mladost. Contract details were confidential but it was assumed that his new contract was worth about 130.000 euros per season.