Luke Littler made history as he became the youngest ever world number one, but had to overcome some early setbacks.The Nuke faced Danny Noppert in the Grand Slam of Darts semi-final as he looked to extend his title defence.Sky SportsA frustrated Littler made his feelings known with an X-rated remark on stage[/caption]Littler is yet to lose a match at the tournament in his career having won on debut last year.A victory over Noppert would both see him into the final and confirm the teenager as the new world number one.However, it was a less than perfect start for the world champion as he lost the opening leg on his own throw.Littler had given himself a three-dart finish after leaving 104 as Noppert waited on 120. The 18-year-old then set up a dart at double 20 by finding 16 and triple 16 to start his visit.He was distracted as he lined up his third dart, though, with cheers heard from the crowd.Littler stepped back to refocus, but could be seen making his feelings known as the camera zoomed in on him.He appeared to say ‘f*** off’ before stepping back towards the oche, only for his dart to land agonisingly below double 20.His frustrations continued as Littler snatched his darts from the board.He could be seen continuing to look towards his family and voice his anger as he returned to his table.Sky SportsLittler was visibly annoyed after missing a dart at double in the first leg[/caption]View Tweet: https://t.co/INctXCEkdBNoppert immediately punished his opponent by taking out 120 on the same double Littler had missed.The Dutchman was then able to hold his throw for the remainder of the first mini-session to lead 3-2 at the break.Although Littler broke back after the restart, Noppert responded to extend his advantage to 6-4 across the next five legs.Littler was able to fight back after the second break, though, as he cut the deficit to a single leg in their race to 16.The teenager managed to race away with it in the end, booking his place in the final with a 16-9 victory.His victory also meant that Littler officially became the world number one for the first time – becoming the youngest to do so (18 years and 299 days) by some distance.Sky SportsNoppert took advantage to break Littler’s throw in the opening leg of the semi-final[/caption]The previous record was held by Michael van Gerwen who was 24 and 251 days in 2014.Who is into the Grand Slam of Darts final?Littler will face 2023 champion Luke Humphries in the final later on Sunday night.Cool Hand beat Gerwyn Price 16-13 earlier in the afternoon in their semi-final meeting.