After a lackluster first half in which the Union found themselves trailing the team with the worst record in Major League Soccer, they came out a much different team for the final 45 minutes.

With C.J. Sapong and Haris Medunjanin scoring second-half goals, the Union defeated the Colorado Rapids, 2-1, before 18,399 on Saturday night at Talen Energy Stadium.

The Union (4-4-4) have won four games in a row and increased their unbeaten streak to six games. Colorado (2-8-1) has lost seven of its last eight.

"It was a tale of two halves," Union coach Jim Curtin said. "The first half was very disappointing, and at halftime I was upset with the performance, and I laid into them a little bit and got the response."

The Union were not playing as a team in the first half, and Curtin was upset that the players were finger-pointing.

"Guys were throwing their hands up at each other and not together," Curtin said. "Mistakes were happening, and guys were getting on each other."

In the 64th minute, the Union got a break when Colorado's Kevin Doyle hit the crossbar from just outside the box on a free kick. After that, the Union took over.

The Union earned a penalty kick when Colorado's Kortne Ford was called for a hand ball in the box, and Sapong converted in the 67th minute to tie the game at 1-1. It was Sapong's eighth goal this season, one shy of his career high, which he achieved twice.

The breaks kept coming for the Union when Colorado's Caleb Calvert was tossed after receiving a red card for two yellows, both in the 69th minute. So, the Union had not only the momentum but a man advantage for the rest of the game.

The Union took a 2-1 lead in the 75th minute on Medunjanin's free kick from just outside the box. The left-footed Medunjanin kicked the ball over the wall and curled it into the right corner for his second goal.

"I knew when I kicked it that it was going in," Medunjanin said.

Rapids keeper Tim Howard stopped a breakaway by Jay Simpson in stoppage time.

Colorado opened the scoring on a goal by Calvert in the 15th minute, breaking a streak of four consecutive shutouts. Calvert was allowed to dribble freely toward the goal and from the top of the box sent a shot into the upper right corner. It was the first career goal for the 20-year-old Calvert.

In the 24th minute, Howard stopped a 12-yard shot by Ilsinho after the Union midfielder received an excellent back pass from Fabian Herbers.

Union midfielder Chris Pontius, who started the first 11 games, replaced Herbers in the 27th minute. Afterward, Herbers said he will have an MRI exam on his groin.

In the 35th minute, Pontius sent a header over the net on a cross from Dutch defender Giliano Wijnaldum, who made his first MLS start at left back. He replaced Fabinho, who had started the previous 11 games.