The Kansas City Royals entered this weekend's four-game series against visiting Detroit looking to cut into the Tigers' lead in the American League Central, but things haven't gone as planned. Detroit won the first two games to increase its division lead to 6 1/2 games over Kansas City, which has dropped five of its last seven. The Royals are also winless in five games against the Tigers in Kansas City this season. The Tigers have won four straight while playing without designated hitter Victor Martinez, who has missed the last five games with a strained back and is not expected to be available this weekend. Martinez, who is hitting .328 with a team-high 21 home runs, has been replaced on the American League All-Star team by teammate Ian Kinsler. Kansas City left fielder Alex Gordon will miss the All-Star game with a sprained right wrist, but is expected to avoid the disabled list.TV: 7:10 p.m. ET, FSN DetroitPITCHING MATCHUP: Tigers RH Rick Porcello (11-5, 3.53 ERA) vs. Royals RH James Shields (9-4, 3.71)Porcello lost out to Chicago White Sox starter Chris Sale in the fan voting for the final spot on the All-Star Game, but he could still be added as a replacement player. The 25-year-old didn't help his chances with his last start against Tampa Bay on Sunday, when he had a 25-inning scoreless streak snapped and allowed seven runs on 11 hits over 5 2/3 innings. Eric Hosmer is 5-for-16 with a home run against Porcello, who owns a 7-3 mark and 4.41 ERA in 16 career starts against Kansas City.Shields is coming off a stellar performance against his former team Monday, when he struck out 10 over seven scoreless innings at Tampa Bay. The outing was encouraging for Shields, who posted a 6.63 ERA in his previous three starts. The 32-year-old is 6-4 with a 4.49 ERA in 16 career starts against Detroit, and Miguel Cabrera (.404), Torii Hunter (.321) and Austin Jackson (.313) have all enjoyed success against the veteran.WALK-OFFS1. Hosmer is 19-for-43 with two homers and six RBIs during his 11-game hitting streak.2. Detroit manager Brad Ausmus left Friday's game in the second inning with flu-like symptoms. Bench coach Gene Lamont took over for the rest of the game. 3. Kansas City is 13-32 when the opponent scores first.PREDICTION: Royals 6, Tigers 4