Liverpool fullback Robertson updated his social media updates and said goodbye to Arnold, who left the team this summer.
Robertson posted a photo with Arnold holding the Champions League trophy and wrote: "My brother, where should I start? I have been honored to witness you grow from a boy to a man in the past 8 years. Along the way, you have won everything and created beautiful memories. I want to thank you for keeping pushing me to new limits and setting the standards so high that I have no choice but to follow your footsteps."
"We will miss you very much on the training ground, and even more so on the court. I hope that the efforts you have made for the club, the wonderful moments you have created for us, and the great contributions you have made, will be recognized as you deserve."
"Let's fly together for the last time."
Note: Wingmen is a program jointly launched by Robertson and Arnold