This much is easy to understand: For No. 24 Georgia Tech to retain real hope of playing for the Atlantic Coast Conference championship, it must beat No. 18 Clemson on Saturday.
Clemson (7-2, 6-1 ACC) also has no margin for error as it chases Florida State in the Atlantic Division. Florida State could clinch its berth in the conference title game by beating Miami on Saturday night. The Seminoles also would clinch if Clemson loses to the Yellow Jackets.
Georgia Tech (8-2, 5-2) wraps up its ACC schedule Saturday. Duke, which beat the Yellow Jackets last month, still has three more league games remaining, including Saturday against Virginia Tech.
Coach Paul Johnson said Georgia Tech must keep winning to put pressure on Duke.
''As I've told the team this week, we've got a huge challenge, but it's our last game,'' Johnson said. ''If we could find a way to win the game, we finish 6-2, and the team in front of us has three games left.
''I think it's long from being over, but you've got to keep applying the pressure. If you lose then your chances become very slim.''
The Tigers beat the Yellow Jackets each of the last two years, but both games were at Clemson. Now Georgia Tech has the home field and a new weapon in quarterback Justin Thomas, a sophomore in his first year starting.
''This quarterback now is better than the one last year in (Vad) Lee, I think because he's got into the system more and it shows in film,'' said Clemson defensive tackle DeShawn Williams. ''He's handled things a lot better. He's a fast guy as well, a little guy, but he also can chuck it deep.''
The 5-foot-11, 185-pound Thomas leads Georgia Tech with 781 yards rushing.
Here are some things to know about the matchup of Top 25 teams from the ACC:
TRIPLE OPTION NO MYSTERY: Clemson coach Dabo Swinney said facing Georgia Tech every year has forced his defense to work against the spread-option offense, with its triple-option plays, throughout the year. ''For us, if it was the first time, it would be more of a challenge, but we do play them every year,'' Swinney said.
STRENGTH AGAINST STRENGTH: Clemson beat the Yellow Jackets in a high-scoring game, 55-31, last year as Georgia Tech rushed for 253 yards. Georgia Tech again is a strong running team and ranks second in the nation with 335.6 yards rushing per game. Clemson, No. 2 in the nation in total defense, ranks fourth against the run, allowing 90.9 yards.
WATSON RETURNS: Clemson freshman quarterback Deshaun Watson, from Gainesville, Georgia, is expected to start after missing three games with a broken bone in his right hand. Watson has 12 touchdown passes in only six games, including three starts, but his ability to beat defenses with his scrambling is another concern for Johnson.
''I think we've struggled with mobile quarterbacks all year,'' Johnson said. ''I think what he does is keep plays alive. He can take a play that looks like it's not going to work and ad lib and create big plays on his end.''
DAYS STARTING: Running back Zach Laskey was a starter for Georgia Tech before missing three games with a shoulder injury. Laskey is listed as probable, but Johnson said Synjyn Days will start. Days has rushed for more than 100 yards in three straight games, including 157 yards with a touchdown in last week's 56-23 win at North Carolina State.
THIRD DOWNS ARE KEY: Clemson leads the nation in third-down defense. Georgia Tech converts 59.3 percent of its third downs - also first in the nation.
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