The Thunder swept the four-game regular-season series against the Lakers by an average of 29.3 points. The Lakers have an uphill battle ahead of them, to state the obvious. Heading into the Lakers’ second-round playoff series against the Thunder, here are three key matchups to keep your eyes on: The Thunder’s Shai Gilgeous-Alexander is the reigning NBA MVP. NBAE via Getty Images Shai Gilgeous-Alexander vs. Marcus Smart Gilgeous-Alexander is the reigning MVP. He’s likely to repeat for that honor when the winner is announced later this month. There’s no stopping him. He’s like a metronome. He’s guaranteed to score about 30 points a game. Smart has an impossible task: trying to slow down Gilgeous-Alexander. The good thing for the Lakers is that Smart is a former Defensive Player of the Year in 2022. He’s used to guarding opposing teams’ superstars. In the only game Kevin Durant played in the Lakers’ first-round series against the Rockets , Smart bottled up the greatest scorer of all time.…