Aryna Sabalenka's 2026 season has been a mix of highs and lows, with her coach Jason Stacy recently admitting to a costly mistake in their training regimen. Despite dominating the tour with back-to-back Masters titles, Sabalenka has struggled to secure Grand Slam success, which has been a source of frustration. As she begins her grass-court campaign at the Berlin Tennis Open, the coach's acknowledgment of the error highlights the challenges faced by the world No. 1. The team is now focused on refining their approach to maximize her potential as the season progresses.