LAWRENCE, Kan. (AP) — The second Saturday of October has a different focus in the Big 12 this season. The big game is No. 17 TCU at No. 19 Kansas in an unexpected matchup of undefeated teams. Texas and Oklahoma play their annual game at the State Fair of Texas with both teams unranked for the first time since 1998. Iowa State’s Big 12-best defense faces against No. 20 Kansas State with Big 12 rushing leader Deuce Vaughn and dual-threat quarterback Adrian Martinez. Texas Tech plays at seventh-ranked Oklahoma State. Baylor and West Virginia have open dates before playing the following Thursday.

Some things to watch in Week 6 of the Big 12 season:

GAME OF THE WEEK

No. 17 TCU at No. 19 Kansas. An unexpected matchup of undefeated teams on the second Saturday in October when the Big 12 is usually focused on the Red River rivalry. Even ESPN’s “College GameDay” is going to be on location in Lawrence, Kansas, not at the State Fair of Texas for Texas-Oklahoma.

Second-year Kansas coach Lance Leipold has already had quite an impact for the Jayhawks (5-0, 2-0 Big 12), who have matched their win total of the past three seasons combined and are now ranked for the first time since 2009. TCU (4-0, 1-0), with first-year coach Sonny Dykes, is coming of a 31-point home win over the Sooners.

This is matchup of two of the Big 12’s most efficient quarterbacks: Jalon Daniels for Kansas and TCU’s Max Duggan, who returned to the starting role after Chandler Morris got hurt in the season opener. Daniels and Duggan have 11 touchdowns each, and only one interception among them (Daniels).

BEST MATCHUP

Iowa State’s Big 12-best defense against Kansas State’s Adrian Martinez and Deuce Vaughn, the conference leader at 127.6 yards rushing per game. Dual threat quarterback Martinez has run 33 times for 319 yards and seven touchdowns, while completing 33 of 53 passes for 350 yards with two TDs and no interceptions as the 20th-ranked Wildcats won their first two Big 12 games. The Cyclones allow only 255.4 total yards and 14.4 points a game.

INSIDE THE NUMBERS

Texas Tech is playing its fifth consecutive Top 25 opponent to match the longest streak in school history (2012). The Red Raiders have split the first two. According to STATS, they are the first team since Ohio State in 1995 to play five ranked opponents in their first six games. … The Big 12’s 11.3 scoring margin in conference games is the smallest of the Power Five leagues. … Iowa State’s Colby Reeder and Kansas State’s Daniel Green are the only Big 12 linebackers with two interceptions.

PLAYER TO WATCH

Oklahoma State LB Mason Cobb is the team’s leading tackler with 30 overall (18 solo, 12 assists) and is the Big 12 leader with 1.8 tackles for loss a game. He also had a big play for the seventh-ranked Cowboys in their 36-25 win at Baylor last weekend, when he stopped running back Richard Reese for no gain from the Cowboys 7 when they had a 9-3 lead about midway through the third quarter.

UNUSUALLY UNRANKED

Texas and Oklahoma play for the 118th time Saturday, and this will be their first meeting since 1998 with neither team ranked. The Sooners had been ranked in 21 of the 24 games since, with Texas ranked 19 times. The future SEC teams each have 931 all-time wins; only Michigan (981), Alabama (947) and Ohio State (947) have more. The Sooners’ all-time record is 931-333-53 since its first season in 1895; Texas played its first game two years before that and is 931-387-33.