KANSAS CITY -- Twins infielder Luis Arraez was diagnosed with a Grade 1 sprain in his right ankle, an MRI exam revealed on Sunday. The Twins will take things day by day and pursue aggressive treatment, though there is no timeline for Arraez's return to action.

Arraez is wearing a protective boot for now, and the ankle is structurally stable enough for game action, but the question is when normal function and range of motion can be restored and how the pain can be managed. Grade 1 is considered the least severe level of sprain.

"He's going to basically be working on flexibility and getting to a point where he's weight-bearing, hopefully, in the near future, and we're going to just start from there," manager Rocco Baldelli said. "It will be another true day-to-day situation. We're going to probably do as much treatment as you can possibly do on someone between now and this Friday, and we'll see where we're at."

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Arraez would almost certainly have been in the starting lineup when the Twins open the American League Division Series on Friday against the Yankees. In that regard, the four off-days between Sunday's regular-season finale and the start of the ALDS couldn't come at a better time for Minnesota.

The Twins don't need to lock in their ALDS roster until Friday morning, and Baldelli anticipates waiting until the last possible moments to set his personnel, which could also involve a decision regarding Ehire Adrianza, who continues to recover from a right oblique strain. Max Kepler and Marwin Gonzalez are expected to be healthy for Game 1 of the ALDS.

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If Arraez is unable to play, Willians Astudillo would appear in line to take the rookie's spot on the postseason roster to provide additional infield depth for the Twins. Arraez's primary positions are second and third base, where Astudillo can offer coverage. Astudillo would also give the Twins an insurance option at first base, where the health of C.J. Cron's right thumb could still be in question.

Though Adrianza has not been swinging at full capacity yet as he recovers from his oblique injury, the 30-year-old utility man would almost certainly make the roster in Astudillo's place if he were to be at full strength by next Friday.

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Arraez injured the ankle when he collided with first baseman Astudillo while attempting to field a popup in front of the mound in the seventh inning of Saturday afternoon's 4-3 win over the Royals.

While Astudillo appeared to be fine after falling to the ground, Arraez grabbed his right leg and remained down for several seconds as Baldelli and head athletic trainer Tony Leo raced out of the dugout. The Twins eventually summoned a cart as Arraez did not appear able to place any weight on his injured leg.

"He's a huge part of the team," said designated hitter Nelson Cruz on Saturday. "Definitely, we're a better team when he's playing. So hopefully, he's ready for Friday."

Arraez is hitting .334/.399/.439 with four homers and 20 doubles in 92 games, and he is one of only six players in the AL this season with three hitting streaks of at least 10 games.

Previewing Twins' playoff bullpen

Instead of using a starting pitcher on Saturday, the Twins took the opportunity to offer several of their relievers the chance for a tuneup in order to get them properly lined up for Game 1 of the ALDS on Friday.

Though the Twins have not yet made any commitments about the composition of their playoff bullpen, that timeline suggests that the eight pitchers that they used in Saturday's bullpen game are in strong position for use in the postseason. Those eight can now rest for two days, throw again on Tuesday's workout day, and rest two more days before Friday's opener at Yankee Stadium.

Those pitchers were Cody Stashak (two innings, one run), Kyle Gibson (one scoreless inning), Zack Littell (one scoreless inning), Lewis Thorpe (one scoreless inning), Trevor May (one scoreless inning), Tyler Duffey (one inning, two runs), Sergio Romo (one scoreless inning) and Taylor Rogers (one scoreless inning).

"The way we were kind of planning things out, there was a group of guys that we wanted to throw [Saturday], because the way it kind of times up, we can give them another day off the mound next week and then they¡¯ll be ready to go on Friday," Baldelli said. "So we didn¡¯t want to push it to [Sunday]."

Adrianza manages regular-season finale

When Twins media entered the manager's office in the visitors' clubhouse at Kauffman Stadium on Sunday, they were greeted by Adrianza, who managed Sunday's 5-4 regular-season-finale loss to the Royals in Baldelli's place.

The injured Adrianza joked that he was ready to slot himself into the leadoff spot of the lineup that he constructed for the game, which Baldelli said was one of the coaching staff's fears when they offered the managerial role to Adrianza on Saturday night. Adrianza also quipped that he had "no idea" what was in the rulebook.

Accordingly, many of Adrianza's teammates weren't entirely convinced that he would actually be managing the game.

"Some of them do. Some of them don't," Adrianza said. "Some of them think I'm playing today. Some of them think this is a joke. They'll find out when we go out on the field."

On a more serious note, Baldelli offered a strong endorsement for Adrianza, who noted that he would be interested in a coaching career following the conclusion of his playing days.

"I think he¡¯s one, he¡¯s got a great baseball mind and I think he¡¯s passionate about this part of the game as well," Baldelli said. "He¡¯s a passionate player, he handles his day to day exceptionally well, exceptional teammate, person and I think players and staff alike connect really well with him."