The Pirates opened the month of May with a three-game sweep and could close it with another if they beat the Minnesota Twins on Sunday afternoon in Pittsburgh.

A big reason the Pirates have kept themselves at or above .500 since April 1 has been an improved offense backing up their talented rotation.

In the first two games this weekend against the Twins, the Pirates scored 16 runs with 23 hits, including 15 in Saturday's 10-9 win.

Pittsburgh will try to keep things rolling and back up one of its best starters so far in right-hander Braxton Ashcraft (4-2, 2.75 ERA), who will oppose Twins righty Zebby Matthews (1-2, 2.37) in the series finale.

"It's just the work before the game (with) the coaches and trusting the guys. The results look pretty good right now," Pirates' first baseman Spencer Horwitz told Sportsnet Pittsburgh after Saturday's game. " ... Everyone knows they don't (always) have to be the guy and if they don't come up that time, you can pass it on to the next guy and trust that they're going to get it done behind you."

Horwitz has been one of the Pirates' hottest hitters this month.

Since May 2, Horwitz is hitting .346 with four home runs and 16 RBIs. Horwitz started Pittsburgh's offensive surge on Saturday with a leadoff homer in the first inning. Bryan Reynolds is also hitting .323 with three home runs and 19 RBIs in May.

The Pirates might also welcome back one of their other big bats Sunday, as Ryan O'Hearn (right quad muscle strain) is expected to be activated from the 10-day injured list, according to multiple media reports. He has seven homers and 29 RBIs in 44 games this season.

Ashcraft, who has never faced the Twins, is 3-0 with a 1.82 ERA over five May starts. He gave up one run on seven hits and one walk while striking out five over 6 1/3 innings on Tuesday against the Cubs.

The Twins have had frustrating results this week as they look to snap a four-game losing streak. On Friday, Minnesota lost despite taking a 5-4 lead into the ninth inning when Reynolds hit a two-run walk-off home run off closer Taylor Rogers. It was the Pirates' first win in 23 games when trailing after eight innings.

On Saturday, Kody Clemens came up a home run short of hitting for the cycle and helped the Twins tie the game after falling behind 7-1 in the second inning. But Minnesota pitching faltered and the Twins took another one-run loss.

Matthews has delivered three quality starts since joining Minnesota's rotation on May 14. In his most recent outing, Matthews struck out six and walked one, but allowed three runs on five hits, including two home runs, over six innings in a 3-1 loss to the Chicago White Sox on Monday.

"I missed my spot pretty bad on both of those homers," said Matthews, who will pitch against the Pirates for the first time. "...So I've just got to be better. Then we adjusted, second, third time through the lineup, (I) was able to kind of limit the hard contact there later on in the game. But I just need to be better early."

The Twins designated right-hander Simeon Woods Richardson for assignment before Saturday's game and recalled rookie righty John Klein from Triple-A St. Paul. Minnesota has seven days to either trade Woods Richardson, who was out of minor league options, or place him on outright or release waivers.