Former Arsenal player Paul Merson believes the club's decision to sell Gabriel Martinelli might weaken their chances of winning the Champions League this season. Martinelli, a Brazilian winger, has joined Saudi Pro League club Al Hilal for a record-breaking £60 million fee. This move follows the departure of Leandro Trossard to Turkish side Besiktas earlier in the summer. Arsenal signed Christos Tzolis from Club Brugge as a replacement but struggled to bring in a high-profile left winger during the transfer window. Mikel Arteta, Arsenal’s manager, had targeted Morgan Rogers, but the young English player chose to join Chelsea instead. Vinicius Junior, a top talent at Real Madrid, also decided to extend his contract after interest from Arsenal. Merson believes that while Arsenal are still strong contenders for the Premier League title, their lack of a standout forward could hurt them in the Champions League. "I think they'll win the Premier League, but I think they'll fall short in the Champions League because of not having that extra person up front," Merson said on Sky Sports. He praised players like Kai Havertz and Jonny Gyokeres but felt they wouldn’t be enough to challenge top European teams. On the left side, Merson noted that Tzolis is a hard-working winger, while Albert Sambi Lokonga (referred to as Eze) is more suited to a central role. "I can't imagine the right-back having a sleepless night thinking about playing against them," Merson added, emphasizing the need for a strong attacking presence in high-stakes matches. Merson also expressed disappointment at the departure of Trossard, calling him a smart and composed player who performed well in big games. Arteta, however, defended the club’s decisions, stating that selling players was sometimes necessary due to playing time and injury data. "We have to understand the amount of minutes those players played and the ones that were injured," Arteta said. "This is what we have and we already have some very good players." Arsenal will aim to maintain their perfect start to the season when they host Xabi Alonso’s Chelsea at the Emirates on Sunday. The match will be a crucial test of their ability to compete at the top level both domestically and in Europe.