After shocking defending champions England in their opening match and knocking out hosts India in the ICC Women's World Cup, giant-killers Sri Lanka are now eyeing the coveted trophy.
"I think it's an open tournament now. Think we have enough chances to beat anyone. If players can continue performances that they have given during group stages, then there is a possibility of going for the trophy," Siriwardene said in Mumbai.
The island nation had upset holders England with a stunning last-ball one-wicket win and sent India crashing out of the World Cup.
Sri Lanka, who finished second in Group A, take on last edition's runners up New Zealand, who are placed second in Group B, in the Super Six qualifiers.
The teams will play at the BKC ground and Siriwardene said, "We haven't played here before. So we will have a few changes. We will take a call tomorrow."
On playing New Zealand, she said, "We know what to expect when we play them. Done all homework.(It is) 50-50 (on) tomorrow's chances."
Her counterpart Suzie Bates said," It has been awesome for women's cricket and for Sri Lanka to come out and have two major upsets in one tournament. We have been following them and we know now what they are capable of.
"We believe anyone in the Super Sixes phase can beat anyone. Going to be a big game for us tomorrow. Exciting to see another team come up and challenge the top four teams."
The White Ferns have played their two warm-up matches at the venue and Bates said she would like to win the toss.
"It does make a difference with the overhead conditions and the dew in the mornings. There is movement. But we have played two warm-up games here, which is good.
"I think we are good enough whether we win or lose the toss to put together a strong enough performance. But obviously I would like to win the toss," she said.