A last-gasp Phil Godman drop-goal secured a 27-24 defeat of big-spending French team Racing Metro after having toppled the Parisians in an astonishing 48-47 victory on home soil.
Edinburgh's fate is not entirely in their own hands as they will need to better Cardiff Blues' result to guarantee knockout rugby in Europe's premier competition for only the second time.
But their encouraging results in Europe lie in stark contrast to their struggles in the RaboDirect PRO12 where they have only won four matches.
And De Luca believes it is the pressure of winner-takes-all rugby that has brought out the best of Michael Bradley's side.
"We seem to have the winning mentality in Europe. Obviously our record in the RaboDirect PRO12 has been pretty poor," De Luca told the Scotsman.
"For example, Glasgow we should have put away at home and they had the knack of closing out a pretty tight game against us at Firhill.
"But to come out on top was a great relief at Metro especially after another tight game. That was only the second time we have won in France (in the Heineken Cup) after Castres three seasons ago. But that Castres result meant nothing in the end.
"Racing Metro wanted to get one back at us after we beat them at Murrayfield and that only made it more impressive that we managed to get the result.
"We have been buzzing since we posted our first away when and we thought this could be the season to get through and do something special.
"We have kept on track and have always put pressure on ourselves which is the biggest kind of pressure.
"We did not play well against Ulster in our last home league game when the performance was unacceptable. We have got to right those wrongs
"We were all pretty excited at the end and there was a lot of relief as well. You could tell what it meant to boys to be guaranteed European rugby after the Six Nations Championship, guys who are both new to the club and those who had been here for years especially as we had become used to dropping out of contention by the halfway stage."
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