6. The big picture: The Purdue-Notre Dame series hasn't always garnered headlines, but as a harbinger of how most Irish football seasons will end up, it's almost scary in its accuracy.
Of the 63 meetings since World War II, 41 Irish squads have passed the Purdue test and gone on to win at an .824 clip for the season. The 22 ND teams that lost to Purdue averaged a modest winning percentage of .536.
Golden Tate's numbers suffered in 2008 when Michael Floyd wasn't in the lineup.
The exception came in 2001, when an Irish team that finished 5-6 beat Purdue, 24-18, in a game that was moved to the end of the season after the Sept. 11 tragedies originally postponed it.
5. After hours: Saturday's prime-time clash is just the sixth night game in Ross-Ade Stadium's 86-year history. Purdue has lost all but one of the previous five, including a 49-28 dismantling in ND coach Charlie Weis' debut season (2005).
Weis is 6-5 in night games.
4. Weird science: Purdue comes into Saturday's game as the third-least-penalized team in the 120-team Football Bowl Subdivision (69 yards), behind only Houston (45 yards) and Navy (65).
Notre Dame, meanwhile, is averaging as many yards per game in penalties (69.7) as Purdue has amassed in three games this season combined. Strangely, that's not necessarily a bad thing.
Weis is 17-8 when Notre Dame amasses more penalty yardage than its opponents, but just 15-14 when it garners the same or fewer penalty yards.
3. Unsung and underrated: Irish safety Kyle McCarthy has emerged as Notre Dame's best defensive player, by far, through its first three games -- both with his consistency and flair for the dramatic.
The lightly recruited fifth-year senior and former high school option quarterback leads the Irish with 27 tackles. And he is the first Irish player since Tom Schoen in 1966 to record an interception in each of the first three games to start the season. His interception late in the fourth quarter on the Notre Dame 4-yard line preserved the 33-30 win over Michigan State on Saturday.
2. Plan B, Part I: In ND's first game without standout wide receiver Michael Floyd, keep your eye on the Irish's leading receiver, Golden Tate, and quarterback Jimmy Clausen. When Floyd missed two games and the better part of a third with a knee injury late last season, Tate's numbers suffered from the extra attention he received from defenses, and Clausen's production severely dwindled.
Weis said he has a plan this time to keep defenses from rolling their coverage into Tate.
1. Plan B, Part II: If the nation's 15th-leading rusher, Armando Allen (ankle injury), isn't able to go, sophomore Jonas Gray (74 yards, 16 carries) and junior Robert Hughes (20 on 7 carries) will get the bulk of the work, with freshman Theo Riddick (19 yards, 6 carries) sprinkled in.
Allen's absence would probably reduce or eliminate ND's use of the Wildcat formation and some other offensive packages that are tailored to the 5-10, 200-pound junior.
Hughes, currently doing double duty at fullback and halfback, was briefly ahead of Allen on the depth chart earlier in their careers. Gray surged to the No. 2 spot behind Allen this fall but has had trouble with both fumbling and blitz pickup.
Weis said Thursday night that Allen's availability would be a game-time decision.
Award-winning journalist Eric Hansen, 48, has been covering college athletics since 1983 and is currently assistant sports editor and the Notre Dame football beat writer for the South Bend Tribune.