Try to engage him in short bursts instead of going toe-to-toe with him. Preventing him from attacking consecutively drastically lowers his damage output.
Jax can dodge all incoming attacks for a very short amount of time and stuns enemies in melee range when it ends. Wait to strike him until after his dodge is finished.
The stats shown on this page clarify some significant Yuumi vs. Jax matchup stats that may help you realize the distinctions between these two champions. Yuumi’s KDA ratio ([kills + assists] / deaths) of NaN is greater than Jax’s KDA ratio of NaN, indicating that Yuumi may be more central to her team's team fighting potential than Jax. This observation is largely a result of the differences in assists.
Yuumi normally has a significantly smaller longest kill spree than her opponent does. Commonly, she receives less damage than Jax. This often reflects different amounts of tankyness, but it can also show that the champ with higher HP has less agility and thus is unable to flee from additional harm when engaged or poked.
Both League of Legends champions are great champions. Both have their pros and cons. In League's current meta, Yuumi usually loses when taking on Jax, with a 41.6% win rate. As a result, Yuumi makes a bad counter to Jax.
While Yuumi does have a much lower winrate than Jax, when facing one another, Yuumi also has a lower learning curve that makes her a less challenging character to develop with. You may get destroyed when picking Yuumi into Jax.
Furthermore, Yuumi also has a great deal of utility and CC, a similar amount to Jax. This often makes her just as valuable during teamfights, especially when facing champions with a lot of burst damage.
While there is not a single best champion in League of Legends, in Yuumi vs Jax matchups, Jax is the better champion with a much lower win rate, less champion complexity, and a similar amount of utility to help out your team members during team fights.
Yuumi is a bad counter for Jax. You will do well by focussing your tactics on increasing your CS and clearing objectives. If you are able to do that, you should hold your own as Yuumi against Jax.
If you would like to truly master Yuumi to counter Jax during both the lane and mid / late game phases of League of Legends, you should keep reading to learn a few extra lessons on this matchup. If you mind the build and suggestions shown above, you will grow your win rate by a lot and be that much closer to League of Legends pro players.
Yuumi most often picks up a lot less CS relative to Jax. Champions who typically don't take much CS typically don't have to have much CS to be valuable teammates, such as sup champs. They are capable of scaling properly off of their abilities and first items alone. Yet, champs with a lot of CS, such as hyper-carries, usually require several high cost items to be effective. In either case, try to do better than the numbers shown on this page to do well.
The best items to focus on in your Yuumi versus Jax build include Redemption, Mikael's Blessing, and Moonstone Renewer. When Yuumi incorporated at least these three items in her build, she performed a lot better when fighting Jax than with many other commonly used counter builds. In fact, Yuumi boasted an average winrate of 41.6% when countering Jax with this counter build.
To have the best likelihood of crushing Jax as Yuumi, Yuumi players should take the Summon Aery, Manaflow Band, Transcendence, Scorch, Presence of Mind, and Cut Down runes from the Sorcery and Precision rune sets. Out of all the rune builds players used for Yuumi vs Jax battles, this mix of runes yielded the highest win rate. Notably, these runes averaged a 41.6% win rate overall.
By default, tips, statistics, and builds on how to beat Jax as Yuumi are shown for all skill levels, merged. If you would like to narrow the statistics and builds to an individual rank, you can use the selection menu located above.