Andre Onana will not be able to withstand attacks from the enemy against Manchester United alone. Teamwork with defenders is very important for Andre Onana. Andre Onana must stay focused as a goalkeeper and turn the mistakes he has made into very important lessons so they don't happen again in the future.
Watching Manchester United, alot of things gone wrong, they suffered too much defeats in friendly games, Erik Ten Hag needs to employ new strategies to beat his opponents. The red devil's needs to upgrade their pattern before EPL starts. Manchester united will suffer alot if they don't change their pattern of game. It's never advisable to play without limits, rather with tradeable formation that would lead to goals.
Andre Onana will concede more goals if he doesn't stay in his box. Just friendly games, he has conceded enough goals to prove that he's never a good replacement the former goalkeeper, David de Gea.