Manchester City took control of their Champions League last-16 tie with Dynamo Kiev with a 3-1 victory in the first leg in Ukraine.
"It's the first time at this stage of the Champions League that we're going into the second leg with a good chance of going through - that's never been the case before - but we need to improve year on, year out".
Zabaleta was one of the unfortunate senior City performers to endure the Stamford Bridge thrashing and he acknowledged Dynamo's lengthy mid-season break from domestic competitions means they have not had similar concerns of late.
"We have similar squad that we played in the last Premier League game - the only player that has recovered is Mangala", he said.
Poroshenko nearly had more to celebrate in the 79th minute when Buyalskiy came close to scoring his second, only to be denied by the superb reflexes of Joe Hart, who made a low one-handed stop to keep out the shot from the edge of the box.
Pellegrini said: "I think in this profession you always get criticism when you don't win but for the manager it is important to take the right decision".
Last Sunday's 5-1 FA Cup defeat at Chelsea should be viewed in a different context because City fielded an understrength side, but the previous two losses to Leicester and Tottenham were damaging to their Barclays Premier League title hopes. Having been eliminated by Barcelona in the round of 16 for two successive seasons, Pellegrini might beg to differ.
"So it's very easy because we are focused on having a season that works this year". The draw of 3.40 could be the best bet, as Manchester and Kiev will both be playing for a much-needed win tonight. Had their FA Cup tie been scheduled on Saturday rather than Sunday ahead of a Wednesday Champions League fixture then Pellegrini may very well have been in the position to field a stronger team.
"We missed a lot of chances, we maybe had some doubt when it was 2-1 but we finally scored a third goal".
The Kiev game will be followed four days later by the League Cup final against Liverpool in a crucial period that could determine whether Pellegrini's last season ends with a trophy.
"The guys were anxious before the game and this worry only disappeared after the break".
Rebrov did not use his side's lack of competitive action - the game was their first since December - as an excuse.