CHICAGO (AP) — The Houston Astros came into Chicago hoping to break one of their few slumps this season in a three-game series with the American League's worst team. Instead, they leave the Windy City reeling after being swept by the White Sox.

Meanwhile, White Sox fans got a glimpse of a potential South Side superstar who had his first big moments for the team.

Rookie Yoan Moncada homered to tie the game in the ninth inning and then drove in the game-winnerwith a single in the 11th to lead the White Sox to 3-2 win Thursday night, completing an improbable series sweep of the AL's best team.

The top White Sox prospect said his 11th inning single wass the first walk-off hit he's had at any level.

"It was something indescribable," said Moncada, speaking through a translator. "My feelings, all my emotions were through the roof when I hit that ball and then when I was running the bases. It was something unique."

In the 11th, Leury Garcia led off with a single past diving second baseman Jose Altuve that was then bobbled by right fielder Josh Reddick, with Garcia advancing to second on the error. Altuve dove again for Moncada's hit off Francis Martes two pitches later but could only watch as the White Sox celebrated moments later near his spot in the infield.

"We're not in a great place right now, we obviously had a tough trip to this city," Astros manager A.J. Hinch said. "We'll move on to the next city and get ourselves right again."

Earlier, Moncada homered in the ninth with one out against Astros closer Ken Giles for his second career home run.

"A star is born," White Sox manager Rick Renteria said. "He's taking some nice swings."

It was the third blown save of the season for Giles, who has converted 22.

"I threw a good pitch," Giles said. "I looked the video, right on the outside corner, right on the black. I have to tip my cap to him. He put a good swing on it and drove it the other way. You can't really be mad at it."

Martes (4-2) took the loss after striking out all three batters he faced in the 10th inning, and then allowing the two singles in the 11th.

David Holmberg (2-3) got the last out of the 11th to earn the win. Carlos Rodon threw his third straight quality start without earning a win.