PITTSBURGH -- The Pittsburgh Penguins look drastically different than they did when Tuesday began after an active first day of free agency that was highlighted by the signing of defenseman Christian Ehrhoff.

The Penguins signed Ehrhoff to a one-year contract worth $4 million shortly after free agency began at noon ET. The 31-year-old defenseman became a free agent when he was bought out of the final seven years of his 10-year, $40 million contract with the Buffalo Sabres.

"Once he was bought out, of course he was going to get a lot of attention," Penguins general manager Jim Rutherford said. "I made the call, like I'm sure several other teams did. I just made him aware that we were interested. … He loved the opportunity to come with the Penguins. He just felt let's give it one-year try with a good team with a chance to win."

Rutherford said he thinks Ehrhoff chose to sign a one-year contract with the Penguins instead of potential multiyear contracts other teams may have offered because he felt Pittsburgh would give him the best opportunity to compete for a Stanley Cup. With defensemen Matt Niskanen and Brooks Orpik, who each signed with the Washington Capitals, lost to free agency, Rutherford said the Penguins were fortunate to sign Ehrhoff at reasonable terms.

Rutherford also said Ehrhoff's signing does not affect defenseman Paul Martin's status with Pittsburgh (Martin can become an unrestricted free agent next year).

"We like Paul a lot," he said. "Hopefully he can play here for several years. But certainly, with Orpik and Niskanen going out and all the good young defensemen we have coming, Paul in the last year of his contract, that gives us a little more protection with Ehrhoff even though he is on a one-year contract."

Pittsburgh did not address its second forward line, which had center Evgeni Malkin's former linemates, James Neal and Jussi Jokinen, leave during the past few days. Jokinen signed with the Florida Panthers on Tuesday, and Neal was traded to the Nashville Predators for forwards Nick Spaling and Patric Hornqvist during the first round of the 2014 NHL Draft on Friday.

"I'm not sure we have to get a top-six forward at this time," Rutherford said. "We don't necessarily need to have our team all set for a playoff run in September. So we'll watch this over a period of time, over the first half of the season. Certainly with the addition of Hornqvist, [forward Pascal] Dupuis can go back on the top six. Spaling may be able to play there too.

"If something comes along and we can figure it out cap-wise, we'll take a look at it, but I'm not going to get anxious about it at this point."

The Penguins did sign three forwards, bringing back Marcel Goc for one season at $1.2 million, and adding former Columbus Blue Jackets right wing Blake Comeau on a one-year, $700,000 deal. Goc had two assists in 12 regular-season games after being acquired from the Florida Panthers, and one assist in nine Stanley Cup Playoff games. Pittsburgh also re-signed Nick Drazenovich to a one-year, two-way contract; Drazenovich played one NHL game, spending most of the season in the American Hockey League.

Despite rumors Pittsburgh was pursuing forward Nikolai Kulemin to play alongside Malkin, Rutherford said "it would take someone getting very, very creative" to make that happen. Rutherford said he does not feel pressured to sign another forward after saying Friday the Penguins would acquire at least two when free agency began.

"I guess there's always a chance [the Penguins could sign Kulemin]," Rutherford said. "As we speak, there's nothing in those regards."

Defenseman Deryk Engelland (Calgary Flames) and forwards Joe Vitale (Arizona Coyotes) and Tanner Glass (New York Rangers) signed elsewhere Tuesday. Engelland played primarily on Pittsburgh's third defensive pairing last season, and Vitale and Glass were mainstays in the bottom six.

Pittsburgh also brought in goalie Thomas Greiss to compete with Jeff Zatkoff for the backup position behind starter Marc-Andre Fleury. Greiss was the Penguins' third signing at a one-year term Tuesday, with his contract worth $1 million.

"We had a really good day today," Rutherford said. "We did have a little concern with our defense. We are very fortunate to sign Christian Ehrhoff to fill that void. … We also wanted to add more depth at goaltending and Thomas Greiss was a guy that I've liked for a long time and he'll certainly be able to add some more depth to that position. Then also with the addition of Comeau … he skates real well, he's got size, and I like that addition."