PEORIA, Ariz. -- With slightly more than one-third of a pitching staff that led the American League in ERA last season leading the way, the Mariners will open Spring Training on Thursday morning at the Peoria Sports Complex harboring high hopes and expectations.

"Of the 31 guys we have in camp, 12 were with our club at some point and time last season," pitching coach Rick Adair said. "The biggest thing is for those guys who know what we're about to be the leaders of this thing, to set the tempo and be a resource for everybody else coming in."

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Among the returnees are ace right-hander Felix Hernandez, who finished second in the AL Cy Young Award race, and right-handed closer David Aardsma, who recorded the first 38 saves of his Major League career last season.

Veteran left-hander Cliff Lee heads the list of newcomers, giving Seattle an awesome one-two punch at the top of the rotation.

"I think they will be good for each other," Adair said, "and I think both of them will have a huge effect on the entire pitching staff. When you are around people who have had success, you pay attention to their body language, how you should go about your business."

Right-hander Doug Fister, one of the 12 holdovers from last season, is looking forward to his first big league camp. He compared the opening of Spring Training to the first day of a school year.

"In a lot of ways it is similar," he said. "You haven't seen your classmates, per se, for a while, and you get see some of your best friends and guys you go to battle with. It's good to be back, get some hugs, catch up and then go to work."

It has been nine years since the Mariners have participated in a playoff game, and there hasn't been this much excitement heading into a Mariners Spring Training since -- two years ago.

The 2008 team was coming off an 88-win season and second-place finish in the American League West. There were visions of a pennant race and the battle cry going into camp was "anything less than a division championship would be unacceptable."

Seven months and 101 losses later ...

A lot has changed since that '08 disappointment, and the lofty expectations are back, thanks to the 85-win season last year and a plethora of offseason personnel changes that many believe will carry Seattle into the playoffs for the first time since 2001.

When the regular position players work out for the first time on Tuesday, there will be more than 60 players in uniform. From that bunch will come the bulk of the 25-man Opening Day roster.

The numerous moves general manager Jack Zduriencik has made since the end of last season, including the acquisition of Lee, the 2007 AL Cy Young Award winner, have lifted the spirits of Mariners fans and been noticed throughout the Major Leagues.

But the GM is being careful not to get carried away with the restructured roster.

"At this moment in time, we haven't proven a thing," Zduriencik said. "It's nice to have had a successful winter, if you will, but as I look at it, we are still the third-best club in our division and it will be very, very competitive."

Manager Don Wakamatsu agrees.

"I think the challenges are just as great this year, if not greater," he said. "The expectations are higher. The biggest challenge we have is that we don't have the same length [of Spring Training] as last year."

Spring Training is almost a week shorter than a year ago, when the second World Baseball Classic was played.

"Everyone says Spring Training is too long," Wakamatsu said, "but I don't agree. I' m a strong proponent of [the idea that] what you are able to accomplish in Spring Training has a bearing on the regular season and the more time you have [in camp], the easier it is to make evaluations on players."

Although a majority of the Opening Day roster spots appear to be occupied by veteran players heading into camp, Wakamatsu warns not to underestimate the power of competition. The goal is to leave camp with the best 25 players.

"I think the way the roster is structured, it would be difficult [for a young player to make the club], but you never know," he said. "There could be an injury here and there. I tell the guys to come in a play. The last thing to worry about is making the club."

Just like last season, introductions are in order.

"There are a lot of new faces," Wakamatsu said. "It's a lot like last year with the new guys, and I have to introduce myself all over again. There are players I have never laid eyes on, so it's important to bring these guys together, the same way we did last year.

"That's all I am worried about right now, getting everyone together. As you know, I believe in that."

Right-handed reliever Brandon League, acquired from the Blue Jays for Brandon Morrow, begins the next chapter of his career in Seattle's bullpen and could wind up with a key role as a late-inning setup man for Aardsma.

Wakamatsu said the day-to-day routine for pitchers will be similar to last season. Lee, returning left-hander Erik Bedard, who recently signed an incentive-laden contract, and right-hander Sean White could be the only hurlers held back a bit. White ended the season on the disabled list with right shoulder tendinitis.

Leaving camp with 11 or 12 healthy arms looms large.

"After talking to [former Major League manager] Chuck Tanner before we started camp last year," Wakamatsu said. "[He said,] 'If you aren't careful, most pitchers won't be ready to start the [regular season].' We tried to make sure guys were ready to go."

The pitching was good from the get-go, and Seattle led the league with a 3.87 team ERA.

Special attention was spent on throwing strikes, establishing a quick tempo, and controlling the running game. The same game plan will be used this season.