Brad Bush prides himself as an offensive-minded football coach, but is wise enough to admit that the key behind Chelsea High School's unblemished start to the season resides on the other side of the ball.

Consider the Bulldogs' latest victory -- a 14-13 nail-biter against Ypsilanti Friday night -- when Chelsea yielded only one offensive touchdown, once again leaving its fate in the hands of a defense that protected a one-point lead for the final three quarters at Jerry Niehaus Field.

The Bulldogs somehow survived, relying on a pair of interceptions in the final 2 minutes of the fourth quarter -- first by Logan Yordanich and then by Tyler Frank -- both which cut short drives during Ypsilanti's last-ditch comeback effort.

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"We just had to step up to the challenge," Yordanich said. "That's what we knew we would have to do from the beginning of the season and we're still doing it now."

For Chelsea (3-0, 2-0 Southeastern Conference) the latest defensive strong-hold proved critical on a night when the Bulldogs' offense produced only 179 yards. The defense provided the game-winning touchdown in the second quarter when senior cornerback Zak Karschnik pounced on an Austin Sanders fumble in the end zone, staking the Bulldogs to a 14-0 lead.

Berkley Edwards' 6-yard run earlier in the first quarter accounted for Chelsea's only other touchdown.

But it wasn't until after Ypsilanti (1-2, 1-1 SEC) answered back with 13 second-quarter points that Chelsea's defense really buckled down.

"I don't think we played at our best," Yordanich said. "We made a lot of mistakes and our No. 1 goal this week was to not let any big plays happen and we let at least eight happen. So we've got a lot of improving to do."

The Phoenix narrowed the gap to 14-13 when Sanders -- who led Ypsilanti with 112 rushing yards on 24 carries -- sprinted 45 yards with 2:15 remaining in the first half that helped nearly erase the early deficit.

Ypsilanti had chances to take the lead throughout the second half. After driving to the Chelsea 12-yard line late in the third quarter, Chelsea's defense stepped up, deflecting a pass in the end zone to kill the drive.

With its offense still struggling to produce, Chelsea again turned to its defense.Ypsilanti appeared to have something going late in the fourth quarter, reaching midfield. That's when Yordanich deflected an Allen Aaerion pass into the air and caught it, returning it to the Phoenix 10-yard line.

But when the Bulldogs failed to reach the end zone, the Phoenix got one last chance - this time with less than a minute to play. But when Kevin Carter tried to find a streaking receiver downfield, Frank made a lunging interception, handing Ypsilanti its second loss of the season.

The Phoenix have now lost two games by a total of two points.

"(The chances) came far and few and Chelsea did a great job of getting pressure on our quarterback and we made some errant throws," Ypsilanti coach Jason Malloy said. "There were some mental things going on, but overall, I'm satisfied with where we're at.

"We knew this was going to be a measuring stick."

While Chelsea's lack of offensive execution was a concern, Bush found solace in another solid defensive effort. Bush spent much of the week trying to convince his players not to look past Ypsilanti, but found himself again turning to his defense to keep the Phoenix from coming up with a late offensive surge that could have handed the Bulldogs their first loss of the season.

"I've told our guys all year that I believe we have to win on defense," Bush said. "As an offensive coach, I would have liked to play better on offense, but we kept playing field position and our defense came through for us and so we'll take the win."

Jeff Arnold covers sports for AnnArbor.com and can be reached at (734) 623-2554 or by email at jeffarnold@annarbor.com. Follow him on Twitter @jeffreyparnold.