Man City failed to win a single away game in the competition last season, and Guardiola is happy that this has been put right in the very first fixture of the 2017-18 tournament.
The Spaniard told BT Sport: "Last season we couldn't win one game away from home and we spoke about that. If we want to make a step forward then we have to be important home and away.
"We had a good performance and it was important to score in the first minute. Offensively and in terms of character we played well. There are a lot of things to do but a start like this is so important.
"We have made a huge effort to buy five players to make that step forward, like all the big teams have done in Europe. It's important to see if we can go away and play with an attacking mentality, not conceding counterattacks."
In the other opening game of Group F, Shakhtar Donetsk claimed a 2-1 win over Italian giants Napoli.