Arsenal, last season's Champions League runner-up, needs only to avoid defeat at FC Porto on Wednesday to reach the knockout stage.
It'll have to do it without captain Thierry Henry.
Arsenal and the fast improving Portuguese team go into their final first-phase game sharing the Group G lead with 10 points. A draw will send them both through.
Third-placed CSKA Moscow is two points back and is at Hamburg hoping one of the leaders will slip because it cannot qualify even if it matches the leaders' points tally. If all three teams tie, Porto and Arsenal would go through on head-to-head results.
If CSKA wins, Porto or Arsenal would exit with defeat.
Henry would have missed the encounter through suspension but the Gunners captain also has a sciatic nerve injury which may keep him out for six weeks.
Arsenal moved up to third in the Premier League last weekend with a 3-0 win over London rival Tottenham, although it is still 10 points behind second-place Chelsea.
Gilberto replaced Henry as captain in that match and scored two penalties. Emmanuel Adebayor and Robin van Persie delivered impressive performances in attack, offering some comfort for coach Arsene Wenger.
Arsenal got its Champions League campaign back on track in the last round with a 3-1 victory over winless Hamburg after being held to a draw by CSKA.
"After the draw against CSKA Moscow we made our job a little bit difficult in the Champions League but the good thing is we depend on ourselves," Gilberto said.
Arsenal beat Porto 2-0 at the Emirates Stadium, when Henry scored his 50th European goal.
But since then, the 2004 European champion has hit a rich vein of form.
Porto opened its campaign with a scoreless draw at home and the loss in London, but then chalked up three successive wins. Two weeks ago it won 2-0 in Moscow, reports AP.
The Portuguese champion opened up a five-point lead at the top of its home league at the weekend with a 2-0 win over local rival Boavista.
That was its fifth straight league win. Porto has 10 wins from 12 games in the domestic league and boasts the championship's best attack and best defense.
Against Arsenal, Porto will likely be at full strength. Right-back Bosingwa, winger Ricardo Quaresma, goalkeeper Helton and striker Helder Postiga, who has scored in each of Porto's last five league games to become the top league scorer with nine goals, are all expected to recover from slight injuries.
Porto won the Champions League under Jose Mourinho before he moved to coach Chelsea, where he has won two Premier League titles.