Arenado will start at third base and bat sixth in Monday's game against the Tigers.

Arenado is in a 3-for-25 rut at the plate, which has dropped his season batting line to .247/.323/.380. As a result of his ongoing struggles, Arenado will be dropped from the cleanup spot for the first time all season. Willson Contreras will hit fourth for the Cardinals on Monday, while Ivan Herrera will bat fifth.

The Cubs designated Lopez for assignment Monday, Taylor McGregor of Marquee Sports Network reports.

The club needed to free a spot on the active roster for Matt Shaw, and Lopez is the casualty. Lopez is just 1-for-24 at the plate this season and is likely to pass through waivers unclaimed, but his solid glovework and defensive versatility should help land him a minor-league contract somewhere.

The Cubs recalled Shaw from Triple-A Iowa on Monday, Taylor McGregor of Marquee Sports Network reports.

Shaw earned another shot with the big club after putting up a .970 OPS, six home runs, five steals and an 11:17 K:BB over 24 contests. He slashed only .172/.294/.241 across 68 plate appearances in his first stint in the majors, but the Cubs seem more confident that Shaw will fare better against big-league pitching this time around. Shaw will take over as the Cubs' primary third baseman, with Jon Berti shifting to a utility role.

Collier (thumb) is in the midst of a hitting progression and appears on track to be activated from High-A Dayton's 60-day injured list at some point in June, MLB.com reports.

Collier has been on the shelf all season after suffering a torn UCL in his left thumb March 13 and requiring surgery. Regarded as one of the top prospects in Cincinnati's system, Collier slashed .248/.355/.443 with 20 home runs over 119 games with Dayton a season ago.

The Cubs are expected to recall Shaw from Triple-A Iowa prior to Monday's game in Miami, Jon Heyman of the New York Post reports.

Shaw was demoted in mid-April after slashing only .172/.294/.241 across 68 plate appearances, but he got back on track at Iowa with a .970 OPS, six home runs, five steals and an 11:17 K:BB over 24 contests. He will get another shot at being the Cubs' everyday third baseman, while Jon Berti transitions back into a utility role.

Riley went 3-for-6 with an RBI and two runs scored in Sunday's 10-4 win over the Red Sox.

Riley was a thorn in Boston's side Sunday, tying the game with an RBI single in the fourth inning while scoring runs in the first and eighth frames. The third baseman is slashing an impressive .300/.355/.429 in May, though he hasn't homered since going deep twice May 4. On the year, he sports a .287/.335/.451 slash with eight home runs, 28 RBI, 23 runs scored and two steals across 209 plate appearances.

Lewis went 1-for-4 with a solo homer in Sunday's 5-2 loss to the Brewers.

The Minnesota third baseman smacked a 417-foot solo shot off Milwaukee starter Freddy Peralta in the fourth inning for his 33rd career homer. Perhaps this performance will break Lewis out of his recent funk. He entered this contest amidst a cold spell, slashing just .200/.263/.229 across 38 plate appearances since returning from a left hamstring strain May 6.

Vargas went 2-for-3 with a solo home run and a hit-by-pitch in Sunday's 6-2 loss to the Cubs.

Vargas tied the game at 1-1 with his fourth-inning solo shot off Colin Rea. Over his last nine games, Vargas has logged five multi-hit efforts, going 12-for-34 (.353) with four homers, four doubles and nine RBI. The infielder is up to a .245/.328/.421 slash line with six homers, 21 RBI, 20 runs scored, 10 doubles and one stolen base over 180 plate appearances. He continues to play on a near-everyday basis amid this recent strong stretch.

Paredes went 1-for-4 with a three-run home run in Sunday's 4-3 win over the Rangers.

Paredes gave the Astros a 4-3 lead they didn't relinquish with a three-run blast in the eighth inning. The 26-year-old has been hot over his past 10 games, hitting safely in eight while collecting six extra-base hits, nine RBI and seven runs scored. On the season, he's slashing .259/.372/.434 with seven homers, 24 RBI and 22 runs scored across 196 plate appearances.

Williamson is out of the lineup for Sunday's game against the Padres.

Williamson started the previous five games but will sit Sunday after going 2-for-18 with a walk and six strikeouts during that span, which has dropped his season-long OPS to .554. Miles Mastrobuoni will take over at the hot corner and bat eighth.