BUFFALO — The Washington Capitals addressed one of their needs ahead of the upcoming NHL trade deadline, acquiring Chicago Blackhawks defenseman Michal Kempny for a 2018 third-round draft pick.

As part of the trade that sent forward Marcus Johansson to the New Jersey Devils in the offseason, the Capitals own the third-round pick of the Toronto Maple Leafs as well as their own selection. The Blackhawks will receive whichever pick is better once the draft order is decided.

Kempny is expected to arrive in Washington late Monday night, and it’s possible he makes his debut against the Tampa Bay Lightning on Tuesday in Capital One Arena.

The 27-year-old Kempny is a rental addition, a pending unrestricted free agent with a $900,000 salary cap hit. Ahead of Washington’s game against the Buffalo Sabres on Monday afternoon, Trotz said General Manager Brian MacLellan could have “more under his sleeve.” MacLellan has now added a defenseman before the trade deadline in all four years that he has held this post with the Capitals.

With this latest acquisition, Washington has the maximum of 23 players on the roster, including eight defensemen, with roughly $837,000 in cap space, according to CapFriendly.com. There’s a sense that the Capitals aren’t done dealing before the Feb. 26 trade deadline.

“We’ll see what he does in the next little while here,” Trotz said.

The Capitals have had two rookies on their blue line, including left-shot Christian Djoos, who has played the majority of his minutes beside John Carlson. With Kempny also a left-handed shot, he could move into that second-pairing role, potentially bumping Djoos down to the third pairing. Djoos would then hypothetically play his off-side beside veteran left-shot Brooks Orpik. That could push rookie right-shot Madison Bowey, still exempt from waivers, down to the American Hockey League to clear salary cap room and allow him to continue getting playing time.

Last week, MacLellan said he planned to weigh improving the roster for this season’s playoff push with what will serve the team best in the future. MacLellan expressed a hesitancy to part with draft picks and prospects, as he did the past two “all-in” seasons.

“The young guys are improving,” MacLellan said. “There’s maybe a little inconsistency there, but I think it’s for us to balance between continuing to develop our young guys and winning. That’s the trick for us.”

Kempny skated in 31 games this season for Chicago, recording a goal and six assists, with a plus-13 rating. He was signed as a free agent by the Blackhawks in May 2o16 after playing 213 games in the Czech League. In 81 career NHL games, Kempny has three goals with 12 assists while recording 34 penalty minutes.

Washington played Chicago on Saturday, and a 7-1 rout at the hands of the Blackhawks reinforced the Capitals’ need for blue-line help. Although Washington is in second place in the Metropolitan Division, it is 5-4-4 in its past 13 games, and its 3.61 goals against per game in that span is the second-highest in the league. The Capitals have allowed 32.7 shots per game this season. In that game against Chicago, Kempny played 18:01, tallying an assist.

“It gives us obviously a little more depth,” Trotz said. “We got to see him a little bit the other day and think he’s a real good skater. He’s a little bit more of a veteran player. … I think he just goes in the mix. We think he’s going to help our D.”

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