Pep Guardiola admitted his side needed the killer instinct of Erling Haaland after they edged out Brentford 1-0 in a nervy encounter that left his side one point behind Premier League leaders Liverpool.Haaland settled the contest in the 71st minute when he punished a slip from Kristoffer Ajer, running from the halfway line to slot the ball under the unfortunate Mark Flekken, who had another outstanding match against the reigning champions.Guardiola has been forced to answer questions about the Norwegian star after a 1-1 draw against Chelsea, and he praised his striker for delivering after an "incredibly tough week".