
Reviewed for patch 7.3d

Favorable matchup
Reviewed for patch 7.3d
Lee Sin gets around with dashes: Resonating Strike to reach the marked target and Safeguard to get in or out. Steadfast Presence stops enemy dashes around Poppy, and Heroic Charge stuns against the walls the jungle puts next to every fight.
When Poppy activates Steadfast Presence, she gains speed and projects a field around her that stops enemy dashes; anyone it stops takes damage and is grounded and slowed. If Lee comes in with Resonating Strike or Safeguard into that field, he stops halfway.
Heroic Charge carries the target forward and stuns them if they hit a wall. Jungle and river fights happen next to walls: if your field stops Lee, there's almost always a wall nearby to chain the charge.
Steadfast Presence also passively grants armor and magic resist, more when you're low on health. Lee mixes physical damage (Sonic Wave) and magic damage (Tempest), and since 7.3d he attacks faster per level; that extra durability lets you survive his combo and answer.
Lee wants to fight early. From level 2, play near the walls of your jungle and save Steadfast Presence for his engage; if he wastes it into your field, the fight tilts your way.
Anyone playing Lee Sin into Poppy should wait for Steadfast Presence before using Resonating Strike or Safeguard on her. Fight in open spaces away from walls, and kick Poppy away from her team instead of diving her marksman while she has the field.

Favorable matchup
Reviewed for patch 7.3d
Lee Sin comes out of 7.3d with more attack speed per level and a harder kick, and he wants to decide the game early. Xin Zhao plays at that same pace: he knocks up with Three Talon Strike, engages with Audacious Charge and, with Crescent Guard, ignores damage from anyone outside his circle.
The third hit of Three Talon Strike knocks the target into the air. If Lee comes in with Resonating Strike, that knock-up interrupts the rest of his sequence and lets you choose the next step.
Crescent Guard damages nearby enemies, knocks back everyone except the challenged target and makes you immune to damage from champions outside the circle. Lee opens with Sonic Wave from range: while it lasts, that ranged damage doesn't reach you and he has to come in.
Audacious Charge launches you at an enemy and slows those it hits. When Lee ganks a lane, you arrive right behind him and his ambush turns into an even fight.
Levels 2 to 4, scuttle and first dragon: you both want to fight early, and your knock-up and ultimate give you the tools to do it. Go where Lee goes and don't leave the jungle to him unanswered.
From Lee Sin's side, don't open with Sonic Wave on a Xin Zhao who has Crescent Guard: go in once he has used it or aim at his team. If the third hit of Three Talon Strike is about to land, leave with Safeguard and come back with Sonic Wave once the knock-up is no longer loaded.

Execution matters
Reviewed for patch 7.3d
Lee Sin decides fights by diving an ally and kicking them with Dragon's Rage, which hits harder in 7.3d. Kindred has an answer: Lamb's Respite creates a zone where no one can die. Without the ultimate ready and close to the ally he dives, there is no answer.
Lamb's Respite creates a zone under Kindred where no unit can die while it lasts, and it heals when it ends. If Lee dives an ally near you, the zone turns a sure kill into a few seconds for your team to answer. Careful: it also protects Lee if he's inside.
Mark of the Kindred marks targets to hunt, and each completed hunt empowers your abilities. If Lee takes camps from you early, mark the ones on his side or Lee himself when your team can help: you don't need to win the duel, you need to complete marks.
Dance of Arrows is a tumble with shots, and Mounting Dread slows. Lee needs to land Sonic Wave to reach you; moving between shots helps you dodge it and fight from your own range.
Against Lee's early pressure, Kindred gives ground. Play the first levels without risking duels and look for fights where your ultimate can protect your team when he goes in.
When you play Lee Sin into Kindred, track her ultimate before kicking: if she has it, make the play away from her or wait until she spends it. Pressure her jungle early, while she still has few marks, and don't hand her easy hunts.