Jon Lester

The Red Sox welcome the struggling Twins to Fenway Thursday night for the first in a four-game series.

Jon Lester (5-8, 5.49) will take the mound for Boston, looking to rebound from an atrocious July in which the 28-year-old posted a 9.36 ERA. After kicking off the month with a strong outing in Oakland, allowing just one run over 6 2/3 innings, Lester has given up at least four runs and failed to make it past the sixth inning in each of his last four starts.

In 21 games with their nominal ace on the mound, the Sox are a disappointing 8-13. Particularly troubling however, have been Lester’s struggles at home this season, where he is just 2-6 with a 7.39 ERA in 12 games. That’s unusual for Lester. In the three seasons prior to 2012, he has been essentially the same at home as on the road. If anything, he’s actually been better at Fenway, with a 3.34 ERA compared to his 3.40 on the road.

His struggles, however, have not been limited to Boston this year. On April 23 in Minnesota, for instance, in his one and only start against the Twins, Lester allowed five earned in seven innings, though the Sox pulled out a 6-5 win. Collectively, Minnesota’s current lineup is hitting .282 with an impressive .413 on-base-percentage in 104 plate appearances against the lefty. While Lester has surrendered just two home runs, the Twins have gotten to him in other ways, boasting more RBIs (17) and walks (17) than strikeouts (14).

Red Sox fans can take heart, however, in knowing that the Twins enter Wednesday with the worst run differential in the American League (minus-84) and plan to send a 29-year-old rookie with just 28 innings of big league pitching experience to the hill Thursday night. After pitching 2 2/3 innings in relief for the Rockies in 2010 and three innings for Padres last year, Samuel Deduno (2-0, 3.13) has made four straight starts for Minnesota, earning wins in his last two outings.

Deduno struggles with his control, but when he can command it he has an excellent curveball, which he throws nearly a 30 percent of the time. The right-hander’s curve is also his out pitch, accounting for an incredible 75 percent of pitches in two-strike counts. He also features a fastball in the low 90s and a slider, which account for 41 percent and 23 percent of his pitches, respectively.

Deduno has not faced any current Red Sox hitters.

Twins vs. Lester (LHP)

Joe Mauer (24 plate appearances): .350 BA/.458 OBP/.450 SLG, 2 doubles, 4 RBIs, 4 walks, 2 strikeouts

Denard Span (21): .333/.524/.333, 2 RBIs, 5 walks, 3 strikeouts

Justin Morneau (20): .263/.300/.474, 1 double, 1 HR, 4 RBI, 1 walk, 6 strikeouts

Josh Willingham (12): .286/.583/.286, 2 RBIs, 4 walks, 1 strikeout

Jamey Carroll (9): .111/.111/.111, 1 RBI, 1 strikeout

Danny Valencia (6): 167/.167/.667, 1 HR, 2 RBIs

Alex Casilla (5): .000/.400/.000, 2 walks

Ben Revere (4): .333/.500/.333, 1 walk, 1 strikeout

Ryan Doumit (3): .667/.667/1.000, 1 double, 2 RBIs

Red Sox vs. Deduno (RHP)

No Red Sox hitters have faced Deduno.