Grayson Allen led Duke with 21 points Friday and has been a sparkplug off the bench for much of the ... X Factor: Duke men's basketball vs. South Carolina After an 87-65 victory against Troy Friday, the Blue Devils will play for their third straight Sweet 16 appearance Sunday night at about 8:40 against No. 7 seed South Carolina in Greenville, S.C. The Blue Zone takes a look at a player from each team who could be the difference-maker in the game.Duke: Guard Grayson AllenWith Jayson Tatum and Luke Kennard entrenched as the Blue Devils’ top two scorers, all eyes turn to Grayson Allen to see which iteration of the junior will appear Sunday night given his up-and-down season. If it is the fiery—yet composed—attacker and sharpshooter that has shown up in key games like Duke’s first round game Friday night, Mike Krzyzewski’s team should be in good hands. If it is the easily-agitated and passive Allen, though, it could bode poorly for the Blue Devils as they face a South Carolina team that is one of the nation’s best at forcing turnovers. The Jacksonville, Fla., native will need to be both a consistent scorer and an alert ball handler to help lead his team to the Sweet 16.Allen’s ability to effectively attack and spread the floor not only leads to easy Duke points, but also creates opportunities for his teammates to step up. Against Troy, the junior’s 21-point performance—which included a 5-of-9 clip from long range—carved out space for senior Matt Jones to have his best game in weeks, as Jones scored 14 points on 5-of-7 shooting. With the Gamecocks keyed in on stopping Allen, Kennard and Tatum, we could see another solid performance from Jones or a similar supporting effort from Frank Jackson or Harry Giles. South Carolina: Guard Sindarius ThornwellSouth Carollina’s offense is far from balanced, as Thornwell averages 21.3 points per matchup—outscoring all his teammates by more than seven points per game—and has scored at least 15 points in every contest since Jan. 18. In order to overcome the depth of Blue Devil roster on both ends of the floor, the 6-foot-5 guard will need to have a monster game. Thornwell certainly has the momentum to do so, as the senior exploded for 29 points in the Gamecocks' first-round victory against Marquette thanks to a 10-of-19 shooting performance. The Lancaster, S.C., native is a threat from everywhere on the floor, as he is both aggressive at the rim—leading the Gamecocks in free-throw attempts this season—and a threat from deep, where he shoots 39.3 percent from beyond the arc. Although the SEC Player of the Year has seven taller teammates, he leads the team in rebounding, possessing the agility and alertness to compete with a talented Duke team. On the defensive end, Thornwell has notched at least three steals in nine games this season and will surely challenge Allen and Jackson to avoid mistakes and make accurate passes.