The Big Ten women’s basketball tournament begins Wednesday in suburban Chicago with a new, five-day format and its largest field ever. Regular-season champion Maryland roars into the Sears Centre as the favorite, with a 21-game winning streak and an 18-0 league record in its first Big Ten season. But the Terps are no sure thing. Six other teams — including the resurgent Gophers, experienced Iowa, rising Northwestern and surprising Ohio State — have won 20 games or more, setting the stage for an unpredictable week.

“It’s as deep as it’s ever been, and I think as talented as it’s ever been,’’ Gophers coach Marlene Stollings said. “I think everybody has the belief that the tournament is wide open, and that’s exciting.’’

Here are four story lines as the tournament begins:

Running the table

Three of Maryland’s starters — including three-time All-America Alyssa Thomas — finished their college careers last season after taking the Terrapins to the Final Four. That created some uncertainty heading into Maryland’s inaugural Big Ten season, but its depth and balance helped it become the first team since 1998-99 to go undefeated in conference play. The fourth-ranked Terps have not lost since Dec. 3 and have a 27-game winning streak against Big Ten teams dating to 2007, when they were part of the Atlantic Coast Conference. They lead the league with 80.9 points per game and have beaten conference opponents by an average of 15.8 points.

In pursuit

Iowa (23-6, 14-4 Big Ten), ranked 14th, and 23rd-ranked Rutgers (21-8, 12-6) are senior-laden teams led by a pair of savvy coaches in Lisa Bluder and C. Vivian Stringer. Northwestern coach Joe McKeown has steadily rebuilt the 24th-ranked Wildcats, who reached 20 victories for the first time since 1995-96. Ohio State has improved dramatically under second-year coach Kevin McGuff and has won 10 of its past 12 games.

Gophers resetting

Stollings said the Gophers (22-8, 11-7) will “hit the reset button’’ after losing their final two regular-season games, at Nebraska and Iowa. She praised her young team for its resilience and noted that the last time it lost two games in a row, it responded with a five-game winning streak. The Gophers will need to play stronger, more consistent defense in the tournament, and their starters — all of whom average 31 or more minutes — must fight off late-season fatigue. The Gophers have made the title game only once, in 2005, and have a 7-20 mark in Big Ten tournament play.

Players to watch

Gophers center Amanda Zahui B. was the media’s choice for Big Ten player of the year, and the 6-5 sophomore has become the most dominant post player in the conference. League coaches picked Ohio State freshman Kelsey Mitchell as MVP; the point guard leads the Big Ten with 24.5 points per game and is the nation’s second-leading scorer. Iowa guard Samantha Logic is among three senior starters who fuel the Hawkeyes’ high-octane offense and has 831 career assists. Former Hopkins High School standout Nia Coffey has led Northwestern’s revival, averaging a team-high 15.8 points and 8.9 rebounds. In what was expected to be a rebuilding year for Maryland, sophomore guard Lexie Brown paced the league’s highest-scoring offense.