What happened: Brazil midfielder Lucas Paqueta has a confirmed muscle injury to the back of his left thigh after imaging tests on Tuesday. He first felt the problem Monday during Brazil's 2-1 second-round World Cup win over Japan, began limping late in the first half, and was withdrawn at the break. The CBF says he has started an intensive treatment protocol under the national team's medical staff.

Why it matters: Paqueta had started every Brazil match at the tournament and is Carlo Ancelotti's primary creative outlet through the middle. His absence forces a reshuffle heading into the Round of 16, with Endrick coming on at halftime and Matheus Cunha and Gabriel Martinelli tried in the role. He also joins Raphinha, already sidelined while recovering from injury, thinning Brazil's attacking options at the worst possible moment.

By the numbers: Brazil entered the knockout stage unbeaten at 3-0 with a plus-margin run, scoring 2.7 and conceding just 0.3 per match over their last five, including a 3-0 result at Scotland on June 24. Japan exit having gone 1-3 across the stretch. Paqueta's withdrawal came at halftime and he missed Tuesday's session as the squad prepared for the Round of 16.

What to watch: Watch for a return timeline from the CBF medical staff and how Ancelotti rebuilds his midfield for the Round of 16, with Endrick, Cunha and Martinelli the candidates to replace Paqueta.

Sources