SEATTLE -- It didn’t take Justus Sheffield long to note who is next up on his schedule as he prepares for his second Major League start.

The Mariners' rookie southpaw will face his former Yankees teammates on Wednesday afternoon at T-Mobile Park. And the opposing pitcher? Big left-hander James Paxton, the starter that Seattle dealt to New York to acquire him and fellow prospects Erik Swanson and Dom Thompson-Williams on Nov. 19.

“It’s crazy, huh?” Sheffield said Sunday with a smile. “I don’t know if it lined up like that on purpose or what, but it is what it is and it’s going to be fun.”

The 23-year-old said that he keeps in contact with many of his former Yankees teammates via social media and is excited to face them. Whether his familiarity provides any edge against the American League East powerhouse remains to be seen, but he’s excited for the opportunity.

"I’m sure it’ll help me a little, but I have to take it like any other team,” he said. “I still have to do my homework and I still have to go out and compete.”

Sheffield, the Mariners' No. 9 prospect, per MLB Pipeline, gave up seven hits and three runs over four innings in his first MLB start on Friday against the Blue Jays. Prior to that outing, he’d pitched three games in relief for the Yankees last September and one game in relief for the Mariners in April.

Getting the chance to finally pitch in a starting role on a regular basis in the Majors for the final five weeks of the regular season figures to help the youngster going forward.

“I just need to keep it going,” he said. “I have to stick to the same routines and get better every day, build off that last one. I went back and watched [my last start] a little, more so what I could have done different and what I want to work on this week.”

While Sheffield’s learning curve is just beginning, Paxton is now seven seasons into his big league career. The 30-year-old is 10-6 with a 4.43 ERA in 23 starts for the Yankees, and he's 5-0 with a 3.56 ERA in five August starts, including wins over the Red Sox, Indians and Dodgers.

“It’s definitely a blast from the past,” Paxton said Tuesday as he prepared to face his former team, which only has seven players remaining from last season. “It’s been great visiting the city again.”

Sheffield hasn’t spent much time pondering Paxton’s progress with the Yankees, but he understands the intrigue of the matchup.

“To be honest, I haven’t paid attention to it too much,” he said. “I’ve heard he’s a great pitcher and I’ve seen him throw a few times. But it’s just crazy how it lined up and it’s pretty funny. It’s going to be fun.”

The Yankees series brings another interesting pitching matchup as well, with Mariners rookie Yusei Kikuchi facing veteran right-hander Masahiro Tanaka on Tuesday in a battle that will draw considerable attention in Japan.

Worth noting

• Right fielder Domingo Santana still hasn’t begun throwing as he continues resting the strained right elbow that landed him on the 10-day injured list on Monday. Manager Scott Servais said that Santana will be shut down for 10-14 days before he begins testing the arm, which had limited him to designated hitter duties from July 27 on, hitting just .122/.259/.265, with two homers and four RBIs in 15 games as DH.

“I don’t want to activate him until he feels completely healthy swinging, and he’s not swinging the bat at all yet either,” Servais said. “He’s letting it calm down.”