Indiana is No. 1 in The Associated Press' Top 25 for the fourth straight week, while Gonzaga moved to No. 2 for the first time in school history.
Both are also ranked 1-2 in the USA Today coaches poll.
The Bulldogs were third last week, matching their previous best ranking.
"The polls mean a lot more this time of year than they do in November, December, even January," coach Mark Few said. "All of us are being judged on the true body of work. It's definitely rewarding.
"It establishes us as a national program, which I believe we have been for the last 10 years. This group has done a great job of competing at that level, winning games at the highest level.”
While the West Coast Bulldogs made some news at the top of the poll Monday, Louisiana Tech, the Bulldogs from Down South, moved into the rankings for the first time since a 13-week run in 1984-85, their only appearance in the poll.
Louisiana Tech, which is 25th this week, was led back then to a ranking as high as No. 7 by a forward named Karl Malone. Gonzaga at that time had a point guard named John Stockton. They went on to become one of the greatest combinations in NBA history with the Utah Jazz, were members of the Dream Team and both were inducted in the Naismith Memorial Basketball Hall of Fame.
The Hoosiers, who have been ranked No. 1 for a total of 10 weeks this season, received all but one first-place vote from the 65-member national media panel.
Gonzaga, which got the other No. 1 vote in the AP poll, was ranked third for the final two weeks of 2003-04.
Indiana received 28 of 31 votes in the coaches poll while Gonzaga received the other three.
Duke moved up three spots to third and is followed by Michigan and Miami, which dropped from second after falling to Wake Forest, the Hurricanes' first Atlantic Coast Conference loss this season.
Kansas is sixth, followed by Georgetown, Florida, Michigan State and Louisville.
Saint Louis, which beat Butler and VCU last week, moved into 18th in the poll, the Billikens' first ranking since being in for one week last season.
Colorado State, which was 22nd and lost twice last week, and VCU, which was 24th, dropped out.