GLENDALE, Ariz. -- Larry Fitzgerald took a moment Tuesday to talk about the retirement of his good friend and former teammate Anquan Boldin.

"It's bittersweet," Fitzgerald said. "He's like a big brother to me."

For six seasons with the Arizona Cardinals, from 2004 through 2009, Fitzgerald and Boldin were among the most formidable receiving duos in the NFL, eventually helping the team reach the Super Bowl.

They became close off the field as well as on it.

"Anquan wasn't a guy to really open up to you, you had to gain his trust," Fitzgerald said before the Cardinals practiced. "If you were able to be lucky to get his trust, he was one of the most loyal people you'd ever be around."

Boldin arrived as a second-round pick out of Florida State in 2003. Fitzgerald came one year later as a touted No. 2 overall selection out of Pittsburgh.

Boldin, Fitzgerald said, "took me under his wing my rookie year, invited me over to the house every single `Monday Night Football.' Those kinds of memories are things I'll always remember."

Then there were the overseas tours for charity.

"We were in Ethiopia, or Senegal, all around the world doing things that are positive and always inviting me to be a part of it," Fitzgerald said. "I'm just happy that I was able to be around him for as long as I was able to and be able to call him a friend. I just hope he's happy and enjoys his retirement."

After his seven prolific seasons in Arizona, Boldin ranks high on the franchise's career lists -- second in receptions (586), second in catches in one game (14), fourth in yards receiving (7,520), first in consecutive games with a TD catch (six) and first in most consecutive 100-yard games (five).

Overall, in 14 seasons with Arizona, Baltimore, San Francisco and Detroit, Boldin caught 1,076 passes for 13,779 yards and 82 touchdowns.

"An unbelievable Hall of Fame career," Fitzgerald said. "Every place he's gone, he's been the best receiver on that team. He's led by example off the field. He's done it the right way."

And then there was Boldin's unmistakable toughness. Fitzgerald recalled the game against the Jets in New York in 2008 when Boldin took a vicious hit to the face, fracturing his nasal membrane and numerous other bones. He required surgery to implant seven plates and 40 screws to repair it.

He missed just two games.

"I've never played with anybody tougher," Fitzgerald said. "He's the most gritty, hard-nosed guy I've ever been around, regardless of position. He's just special that way. He might have broke the mold on that type of player. He was cut from a different cloth."

Fitzgerald was asked to pick the one most important thing he learned from his friend.

"Everything is always done to the highest standard," Fitzgerald said, "and he holds himself to that kind of expectation no matter what he does, as a father, as a husband, so when you see that everything he does is always done at the highest level, I need to be able to do stuff like that.

"I think that was the one thing that really always stood out to me, his level of excellence in everything he does and how much pride he took in what he was doing."