Sri Lanka vs Pakistan - whichever team triumphs in the Welsh capital of Cardiff will join title-holders India as one of the two Group B qualifiers for the semi-finals of a tournament featuring the world's top eight one-day international teams.
Sri Lanka are having to shore up their top order after injuries saw both Chamara Kapugedera and Kusal Perera ruled out of the remainder of the Champions Trophy, while vice-captain Upul Tharanga, an experienced batsman, is completing a two-game ban.
Monday's match had the look of a 'dead rubber' after both sides were beaten first up, with Pakistan suffering a 124-run thrashing by arch-rivals India.
But they too bounced back, defeating top-ranked South Africa.
Now Pakistan are just one game away from a semi-final with either tournament hosts England or Bangladesh and a wary Mathews said: "We all know they're a very dangerous team.
"There's no room for complacency in this kind of tournament."
It was Pakistan's attack, a well-balanced mix of spin and speed, that put them in a position to beat South Africa and skipper Sarfraz Ahmed will look to his bowlers to repeat that performance against Sri Lanka.
The live action of the match will be shown of the Star Sports network from 3pm while the live streaming of the match can be caught on Hotstar.com
You can also check out Cricketnext's Champions Trophy 2017 LIVE blog for all the latest action from the match including live scores, ball-by-ball commentary and analysis.
The weather is forecast to be cloudy but dry and rain is expected to stay away. A new pitch will be used for this match. 300 has been about par in the two matches played in Cardiff so far.
Sri Lanka Team: AD Mathews*, WU Tharanga, LD Chandimal, DM de Silva, N Dickwella†, ANPR Fernando, DAS Gunaratne, MD Gunathilaka, KMDN Kulasekara, RAS Lakmal, SL Malinga, BKG Mendis, NLTC Perera, S Prasanna, PADLR Sandakan
Pakstan Team: Sarfraz Ahmed*†, Ahmed Shehzad, Azhar Ali, Babar Azam, Fahim Ashraf, Fakhar Zaman, Haris Sohail, Hasan Ali, Imad Wasim, Junaid Khan, Mohammad Amir, Mohammad Hafeez, Rumman Raees, Shadab Khan, Shoaib Malik