Luke Littler’s World Series of Darts Finals match against Nathan Aspinall was halted as the referee gave fans a telling off.The 19-year-old was facing Aspinall in the last-16 of the competition when whistles were heard coming from the crowd in Amsterdam.The referee stopped Littler’s match to warn fans who were whistling whilst he was throwingNot known, clear with picture deskSo, during the fifth leg of the fifth set, referee Charlie Corstophine stepped in to help out the players at the oche.Not for the first time at the World Series of Darts Finals, fans were whistling whilst Littler threw his darts.He had goaded the Dutch fans just the day before on Friday by putting his hands to his ears during his win over Danny Noppert.But on Saturday, the whistling continued and Corstophine made sure to cut it out with a stern warning sent out. What did the referee say to the fans?The referee faced the crowd, pointed towards them and announced: “Ladies and gentlemen, please, out of respect to both of the players, please do not whistle whilst they are throwing. Thank you.”Thankfully for Littler, he managed to overcome the whistling to beat Aspinall in a last-leg thriller – winning the match 10-9.Speaking post-match, the teenager said: “I said I was just going to get my head down, focus on it, because we know what Nathan is like, he’ll push me all the way and that’s what he’s done there yet again.“I only played well in the last session [from 6-6 onwards]. In the first two sessions, I didn’t feel confident but I managed to get it to 6-6 and I was very good in the third.”What else have World Series fans done? As mentioned, whistling from the Amsterdam crowd has already happened at this year’s World Series of Darts.Littler has already hit back at those whistling, while James Wade also put his hands to his ears earlier on Saturday night after having some of the same treatment during his win over Wessel Nijman.Littler has overcome some tough conditions to reach the quarter-finals in AmsterdamGettyAnd former Dutch darts star Vincent van der Voort has even hit out at his home crowd for their booing at the event too.He said on the treatment of Littler during his recent match with Noppert: “Why do you have to boo him so much as a crowd?“You’re not giving him enough respect for how big this lad already is. You should be happy he’s here. He’s a truly unique player. We’ve never seen this before.“You know you’re for Noppert. Fine. But you don’t have to boo him like that. Just get behind Noppert fully. They were more busy trying to get to him than cheering on Noppert.”Littler keeps clean sweep hopes aliveLittler managed to overcome the whistling and booing against Noppert and then he did the same against Aspinall. The last-16 tie against his good friend went to a deciding leg, but the world number one managed to win it.Littler managed to beat Aspinall in a tense affair to keep his clean sweep dream aliveGettyAnd that victory meant more than just booking a place in the quarter-finals of the World Series of Darts against Jonny Clayton.It helped keep Littler’s dream of history alive, as he still has the chance to complete an incredible clean sweep.If he wins the World Series, the World Grand Prix and European Championship, he would become the first player ever to hold every single major darts title at the same time.And then if he goes on to succeed at the Grand Slam of Darts and Players Championship Finals, he would have won every title in 2026, achieving something even Phil Taylor didn’t manage.Speaking after beating Aspinall, he mentioned his run, telling ITV4: “I’m glad the streak is still on.”