We devise a new proximity junction configuration where an
/s/-wave superconductivity and the superconductivity of Sr_2
RuO_4 interfere with each other. In order to explain the
observed extraordinary temperature dependence of the
critical current in a Pb/Ru/Sr_2 RuO_4 junction, we propose
a competition effect involving topologically distinct
superconducting phases around Ru inclusions. This work is
done in collaboration with Taketomo Nakamura, R. Nakagawa,
T. Yamagishi, S. Yonezawa, T. Terashima, and M. Sigsrist.