Germany provided the first goalless draw, England earned the first comeback victory and Ukraine became the first team to be eliminated from the European Championship on Thursday.
World champions in Brazil two years ago and 2-0 winners over Ukraine on Sunday, Germany went into its Group C game against Poland at the Stade de France as the clear favorites.
Instead, Germany was kept in check by a well-organized Poland side that also had the best chance to break the deadlock in a dour game.
Arkadiusz Milik, who had scored Poland's winner against Northern Ireland on Sunday, miscued a header as he fell to his knees in Germany's goalmouth and the ball bounced wide.
"We created few chances today," Germany coach Joachim Loew said. "We didn't increase the tempo and then nine of 10 Poles were behind the ball."
For a second match running, Gareth Bale scored with a long-range free kick to put Wales 1-0 up in a match. But unlike its opening-game win over Slovakia, this time there was only disappointment after the break as England substitutes Jamie Vardy and Daniel Sturridge turned the match around for a 2-1 victory.
England coach Roy Hodgson doesn't have a reputation as a hardened gambler when it comes to substitutions. So the sight of Vardy and Sturridge walking on for the second half, instead of Harry Kane and Raheem Sterling, was little short of astonishing.
With teenager Marcus Rashford then replacing Adam Lallana in the 73rd minute, Hodgson ended up deploying three forwards plus Manchester United striker Wayne Rooney in a playmaking role to try to shake things up in the Group B match. It worked.
Vardy levelled in the 56th minute and Sturridge rifled home the winner from a similarly close range in stoppage time.
"We made the decision (on the substitutes) early. It was the right decision," Hodgson said.
"We were anxious to inject a little bit more tempo and pace into our game, and we were anxious to persuade the players to take a few more risks and to show more confidence in themselves in the penalty area."
Northern Ireland later claimed its first tournament victory in 34 years with a 2-0 win over Ukraine. With the loss, Ukraine became the first team in the tournament assured of not advancing to the knockout stages.