Just days after being linked with a number of City’s Premier League rivals, Guidetti bagged three in the Eredivisie’s blue-ribbon fixture to take his tally to 14 goals in 13 outings.
Despite falling behind, the 19-year-old leveled things from the spot on the half-hour mark and gave his side the lead four minutes prior to half-time before settling the match with a third late in the second half.
Vladimir Weiss also got his name on the score-sheet during what proved to be a productive weekend for City’s overseas loan stars.
The Slovakian winger pounced on a mistake by Mallorca goalkeeper Dudu Aouate and was left with the easiest of finishes as he tapped home the only goal of the game to secure Espanyol all three points against their ten-man opposition.
There was less luck on the continent for Roque Santa Cruz, however, as his Real Betis side suffered a 1-0 home defeat at the hands of lowly Granada.
Both Emmanuel Adebayor and Dedryck Boyata progressed through to the fifth round of the FA Cup this weekend with both on-loan Blues playing their part.
With both Manchester sides now out of the competition, Manu’s Tottenham will fancy their chances of winning some silverware, but they only just booked their place in the next round, struggling to a 1-0 win at Watford.
Though the score-line doesn’t reflect it, Boyata’s Bolton progressed much more routinely with a 2-1 win over a much-changed Swansea side.
They will now be hoping to go one better than their semi-final appearance last season
The only Blue in domestic league action was Bristol City’s Ryan McGivern. The Northern Ireland international played 85 minutes of the Robins' 1-0 defeat to Reading after being sacrificed towards the end as City sought to claim a late equaliser.
Finally, 20-year-old Mohammed Abu has joined German Bundesliga 2 outfit Eintracht Frankfurt on loan for the remainder of the season.
The Ghanaian midfielder – currently representing his country at the African Cup of Nations – was voted Player of the Year during his loan spell at Norwegian side Stromgodset earlier in the season.