Neither was done with much conviction as City stuttered past West Brom to strengthen their grip on the final Champions League spot.
Yaya Toure and Kevin de Bruyne had to be summoned from the bench for the final half hour as the Baggies threatened to claim their first point at the Etihad in more than 10 years.
The City pair at least had 60 minutes’ rest before they were brought on to rescue a victory — with De Bruyne making a crucial contribution to Samir Nasri’s winner six minutes later.
Pellegrini also left out Bacary Sagna, Gael Clichy, Fernandinho and David Silva from the side that drew 2-2 in their quarter-final first leg with PSG.
Influential skipper Vincent Kompany is also battling to be back for the second leg and Pellegrini must be prepared to take a chance on the Belgian after another unconvincing performance from his back-four.
The Chilean was relieved at full time that his plan to rest some players had paid off.
“It was very important because it was our target to win the three points,” he said, “It was very important to choose the starting XI — players that were tired, players that just work today, players that were coming like Nasri and Fabian Delph from months without playing.”
West Brom did their best to upset the strategy with former Manchester United players Ben Foster, Jonny Evans, Darren Fletcher and James Chester almost doing their old club a massive favour.
Fletcher, in particular, strode around the Etihad with supreme confidence.
The Scot began the counter-attack that led to West Brom’s goal when James McClean’s cross found Stephane Sessegnon, whose fierce shot bamboozled a motionless Joe Hart at his near post.
Sessegnon then threw away the visitors’ advantage with a clumsy challenge on Aleksandar Kolarov that led to the equaliser from the penalty spot — Sergio Aguero confidently converting for his 18th goal of the season.
West Brom boss Tony Pulis was unhappy with the decision and furious with another appeal in the second half that wasn’t given when Eliaquim Mangala clattered into the back of Sandro.
“I thought it was a penalty,” he said. “It does not just affect us as a result, but all the teams around City who are fighting for the Champions League when there are millions at stake — they will be disappointed with that decision.”
It was a crazy and unnecessary challenge from the £42m (€52m) defender and showed why Pellegrini would be prepared to gamble on Kompany who has been out for a month with a calf injury.
Mangala and Otamendi were unconvincing again and can’t expect PSG striker Zlatan Ibrahimovic to have another off-day tomorrow as he did in Paris last week.
The pair were troubled throughout — failing to deal with crosses tossed in from McClean and Sessegnon and panicky as City held on for the three points.
Saido Berahino twice got around the back of the them, screwing his efforts off-target while McClean flashed a volley inches wide with virtually the last kick of the game.
There was relief at the final whistle and delight for matchwinner Nasri, who made his first start in seven months and scored his first goal in eight.
It has been a frustrating season for the Frenchman, who has had surgery on a nasty tendon injury in his groin, and Pellegrini admitted he was delighted for the midfielder.
“I’m very happy for him,” added the City boss, who took him out of his Champions League squad because of the seriousness of the injury.
“He was working very well and he returned sooner than the doctor expects.
“I was also very impressed that he played the 90 minutes. He was a very important player and I am very happy with him.”
Hart 5, Zabaleta 6, Mangala 6, Otamendi 6, Kolarov 6, Fernando 6, Delph 6 (Toure 60, 7), Navas 6, Nasri 7, Aguero 8 (Clichy, 89), Bony 6 (De Bruyne 60, 7).
Caballero, Fernandinho, Demichelis, Iheanacho
Foster 7, Dawson 7, McAuley 7, Evans 7, Chester 6, Fletcher 8, Sandro 6, Sessegnon 7 (Leko, 80), McClean 6, Berahinho 6, Rondon 6 (Gardner 21, 6).
Myhill, Olsson, Yacob, McManaman, Anichebe.