Northampton centre Dom Waldouck believes his side needs two 'big results' to stay in contention for a Heineken Cup play-off berth.
The Saints host Top 14 side Castres in their Pool Four encounter at Franklin's Gardens on Friday.
Ulster are in first position in the pool's standings with 15 points while Castres are second on 12 and the Saints are third on 10 points.
After this weekend's match Northampton travel to bottom-placed Glasgow Warriors eight days later and Waldouck believes these two fixtures are golden opportunities for them to upset the odds and reach the tournament's knockout stages.
"It's a huge competition for us and we're still alive," he told the Northampton Chronicle and Echo.
"We need two big results in the next two weekends and hopefully we can take some momentum into the Heineken Cup and into the rest of the season."
The momentum Waldouck is referring to is the Saints' 30-19 victory at Exeter last weekend - a result which silenced their critics after a fine display.
Waldouck said the criticism from some members of the media was used as motivation ahead of the clash with the Chiefs.
"We've had a lot of criticism in the media, Sky Sports had been on to us," he explained.
"We'd lost by a point the week before to the top team in the Premiership (Saracens) and we'd come under a lot of criticism so it was important to go out on Saturday and prove that we believe in ourselves.
"There aren't many trophies won in January so we can make a push at the end of the season."