SANTA CLARA, Calif. (AP) -Shawntae Spencer was as surprised as anybody when he opened the regular season as the starting right cornerback for the San Francisco 49ers.

But there was nothing surprising about the way he played during the 20-16 win against the Arizona Cardinals in Spencer's first start since 2007.

Spencer held up strong against the receiver tandem of Larry Fitzgerald and Anquan Boldin and helped contain an Arizona passing attack that ranked second in the NFL last season.

Spencer played well in coverage and was second on the team with five tackles. He helped fill the void left by Walt Harris, the team's starter at right corner since 2006 who was lost for the season when he tore knee ligaments in May.

``Shawntae is better than he's ever been since he's been here,'' 49ers coach Mike Singletary said. ``He's playing great technique. He's not making mistakes or mental errors. He's playing with a tremendous amount of confidence and doing a good job all the way around.''

Spencer has made a quick return to prominence in a secondary where he once was considered the team's No. 1 cornerback.

Spencer started 39 games for the 49ers from 2004-2006, but he moved into a reserve role after the team brought in high-priced free agent Nate Clements to play left cornerback in 2007.

Spencer missed five games to injury that season, then had his season end last year in Week 2 when he tore the ACL in his left knee. He had surgery in early October and went on injured reserve.

Meanwhile, other cornerbacks passed him on the depth chart. Tarell Brown played well as San Francisco's No. 3 cornerback in Spencer's absence last year, and the 49ers brought in two-time Pro Bowler Dre Bly after Harris was hurt this spring to compete for a starting position.

Spencer was not the top candidate to win the job at right cornerback this summer as Bly and Brown appeared to be the front-runners at the position. Bly started each of the team's four preseason games at right corner.

But Spencer's work did not go unnoticed as coaches moved him to the front of the line for the season opener. He validated that decision with his steady performance against the Cardinals.

``He played very clean in everything he did,'' defensive coordinator Greg Manusky said. ``He went out there and competed after the surgery that he had a year ago and we were excited about him and happy for him that he got the start. Then he went out (last week) and played and performed like he normally does.''

Spencer wasn't expecting to get the starting call, but he was ready when it came. With Bly and Brown moving into reserve roles, Spencer's re-emergence has strengthened the back end of San Francisco's defense.

Spencer said it felt like old times once he got in the flow against Arizona. Spencer led San Francisco in interceptions in 2005 and was fourth on the team in tackles in both 2005 and 2006 before injuries derailed his next two seasons.

``I'm just back out there doing my job,'' Spencer said. ``I've always played with confidence regardless of what my role was. I've just continued do what I've always been doing. I haven't changed anything.''

Spencer and the rest of the San Francisco secondary face another test this week when the Seattle Seahawks come to town for an early NFC West matchup.

With free-agent receiver T.J. Houshmandzadeh added to the mix this season, the Seahawks had 279 yards passing during last week's 28-0 win over St. Louis and will bring the NFL's sixth-ranked offense to San Francisco.

But the 49ers' secondary will be ready. Spencer already is providing the team with confidence at a position that was considered one of San Francisco's biggest question marks entering the season.

``Shawntae's been in the fire before,'' Clements said. ``He knows what the deal is. Just look how he played (against Arizona). I'm confident in him and we're all confident in each other that we can go out there and get the job done.''Copyright © 2005 The Associated Press. All rights reserved. The information contained in the AP News report may not be published, broadcast, rewritten or redistributed without the prior written authority of The Associated Press.