The Lake Show is only in its fourth day, but Junior Lake has basically sealed a spot on the Cubs’ roster. Leading off for the first time, Lake hit his first major league home run, drove in three runs and collected four hits Monday in the Cubs 4-2 win over Arizona at Chase Field. Has manager Dale Sveum seen enough to say Lake is here to stay? “Right now I’d be pretty stupid to say no,” Sveum said. Chris Rusin got the win while replacing Matt Garza, throwing five-plus innings and allowing two runs on two hits. Lake became the first Cubs player since Andy Pafko in 1943 to have nine hits in his first four games, and the first Cub with four hits in his first four games since catcher Steve Lake on April 26, 1983 against San Diego. He’s hitting .529 so far, and two of his hits were bunts that he beat out, while the home run landed in center field nearly 430-feet away. Asked if he’s won a spot, Lake replied: “I’m still going to keep working hard to make (the front office’s) decision hard.” But so far, it’s a no-brainer. “He’s taken advantage of every mistake,” Sveum said. “He’s laid off some tough sliders, and obviously bunted and has done a great job.” Rusin was Lake’s teammate at Iowa, and has seen what the kid can do. “He’s always going 110 percent, flying around the bases,” Rusin said. “He’s just a tough out. He bunted for his first hit, and hit a home for his second hit and bunted for his third hit. It’s tough to know where to play the guy and how to pitch the guy.” Lake started out as a shortstop and was moved to third, a position he could probably step into when David DeJesus returns next week. But right now Sveum said Lake “might have found his niche” in center. “He’s going to have to play his way out of it,” he said.