Illinois (25-8) opened its NCAA Tournament run Thursday in Greenville, South Carolina, with the kind of performance it needed, pulling away from Penn in the second half for a convincing 105-70 win.For much of the first half, the game was competitive. Penn played with energy, hit enough shots to stay close and did a good job keeping Illinois from fully settling in offensively. The Illini controlled the game, but their 40-30 halftime lead didn't feel irreversible, especially in March, when even favorable matchups can turn tense in a hurry.That changed quickly after the break.Illinois came out of halftime looking sharper, faster and much more connected on the offensive end. The floor opened up, the ball moved with purpose and the Illini started turning good possessions into great ones. What had been a manageable 10-point game quickly became a lopsided one as Illinois overwhelmed Penn with its shot-making, size and overall talent.…