PARIS, Aug 13 (Reuters) - The arrival of Lionel Messi at Paris St Germain has created a positive mood at the Ligue 1 club but he is unlikely to play any part in Saturday"s home game against Strasbourg, coach Mauricio Pochettino said. Speaking at Friday"s news conference ahead of the league fixture after Messi joined PSG from Barcelona earlier this week, Pochettino added his first task was to make sure a star-studded outfit began to look the sum of its parts. PSG surrendered the French league title to Lille last season and were eliminated in the Champions League semi-finals by Manchester City despite boasting the likes of Neymar, Kylian Mbappe and Angel Di Maria in their ranks. Adding Messi to the fold will have raised expectations among fans and the board at the Qatari-owned club, whose management have invested heavily in a bid to see the club win their maiden title in Europe"s premier club competition. But Pochettino, who took over at PSG midway through last season in January, struck a note of caution after 34-year-old Messi arrived from Barcelona, his only previous professional club. read more "Our challenge now is to ensure all of these top players form a team capable of meeting all the challenges ahead of it," said Pochettino. "We want to make sure that this team becomes a strong unit. "As for when we might see Leo Messi in action, it is his second day of training after a month since he played the last game at the Copa America. "We will take things step by step, get to know each other and have him feel fit and comfortable so that he is able to make his debut when he is fully fit." Messi, who won 10 LaLiga and four Champions League titles during a 17-year long stint at Barcelona, led Argentina to the Copa America title with a 1-0 win over hosts and traditional rivals Brazil in the July 11 final. When asked about the future of striker Mbappe, who has been linked with a move to Real Madrid either during the current transfer window or next summer when his contract with PSG expires, Pochettino said: "Kylian is our player. "We all know that Leo Messi is the best, or one of the best players in the world, without any doubt. Nevertheless we have other players as well and Kylian is also one of the best players in the world."