Dietmar Hamann has urged Julian Nagelsmann to ensure Bayern Munich starlet Lennart Karl is on the plane for the upcoming World Cup, claiming the teenage sensation already plays like a veteran. The former Liverpool and Germany midfielder believes the 18-year-old offers a unique threat that the national team simply cannot do without on the biggest stage.Karl has taken the footballing world by storm, parlaying a handful of senior appearances for Bayern into a spot in Julian Nagelsmann's latest Germany squad. The 18-year-old has been selected for the upcoming friendlies against Switzerland and Ghana, a move that signals he is firmly in the frame for the upcoming World Cup.Former Germany midfielder Hamann has been leading the calls for Karl’s inclusion in the final tournament roster. Assessing the youngster’s impact, Hamann told Sky Sport that the teenager possesses a rare natural talent that the national team simply cannot overlook."He's 18 and has only been playing professionally for eight or nine months, but you get the feeling that there's a seasoned pro on the pitch," Hamann said. "Everything he does has a naturalness and ease. With his ability to outmaneuver opponents one-on-one and create numerical superiority on the wing, we simply can't afford not to take him to the World Cup, given the players we have available."While Karl's inclusion has been met with excitement, Hamann admitted he was less convinced by some of the other names on Nagelsmann's list. Specifically, the former Germany international pointed to the inclusion of Leroy Sane and Pascal Gross as decisions that raised eyebrows, particularly given Sane's recent struggles to find a consistent starting role at Galatasaray."The nominations of Gross and Sane surprised me," Hamann admitted. "We don't need to talk about Sane's abilities, but he hasn't been starting in Istanbul recently. Regarding Pascal Gross, his nomination surprised me. If Nagelsmann sees him as a connecting man in the squad, he will probably take him to the World Cup. Then his return to Brighton was worth it."Add GOAL.com as a preferred source on Google to see more of our reportingKarl will have the opportunity to prove his worth on the training pitch this week before Germany face Switzerland. With the World Cup looming, these friendlies represent a final audition for several fringe players. Karl enters the camp in excellent form, having recorded one goal and two assists in his last three appearances for Bayern in all competitions. After facing Switzerland, Die Mannschaft will prepare to face Ghana on March 30.