Kai Havertz fired Chelsea through to the Champions League last-16 stage as his second-half strike secured a hard-fought 2-1 victory against Salzburg.Mateo Kovacics first-half effort gave the Blues the lead, but the hosts hit back swiftly in the second half, Junior Adamu capping off a fine counter-attack.Goalkeeper Philipp Kohn was called upon in both halves to keep the visitors at bay but could do nothing with Havertzs winning effort, as the Germany international drilled in to end Salzburgs 40-game unbeaten home run.Victory means Chelseas spot in the knockout stages is confirmed, while Graham Potters side could J.C. Jackson Jersey still be confirmed as group winners if Dinamo Zagreb fail to beat Milan in the Croatian capital. Opportunities were few and far between until Chelsea took the lead after 22 minutes, Kovacic drilling a shot into the top-left corner after the ball fell kindly to him just outside the area.Three minutes after the break, Salzburg equalised on the counter as Maximilian Wobers superb cro s-field pa s found Adamu and the 21-year-old jabbed a first-time finish past Kepa Arrizabalaga.Adamu then had a major impact at the other end, superbly clearing Jorginhos header off the Los Angeles Chargers Pet Gear line to prevent the visitors swiftly retaking the lead.There was no denying Havertz three minutes after the hour mark, however, as he collected Christian Pulisics pa s just outside the box and fired home a fine finish in off the left post to leave Kohn helple s.The hosts had chances for an equaliser, notably with Thiago Silva needing to be alert to clear Strahinja Pavlovics header off the line as the Chelsea defence stood firm.What does it mean? Blues book their spotAfter defeat in their first group-stage match, which ended up being the final chapter of Thomas Tuchels stint at Stamford Bridge, Chelsea have fought back under new head coach Potter to secure their spot in the Chase Daniel Jersey last 16.That is no small feat after being placed in a group alongside Serie A champions Milan and a Salzburg side who, until Chelseas trip to Austria, had been recently formidable at home in all competitions.Potter still has work to do with the squad, however, with creativity in front of goal still a cause for concern. While the Blues had 10 shots on target against Salzburg, they only created two big chances defined by Opta as a situation where a player should reasonably be expected to score.Potter remains unbeatenVictory against Salzburg extends Potter Brandon Facyson Jersey s unbeaten run at the helm of the Blues to nine matches, securing six wins and three draws so far.That makes Potter the second English bo s to achieve the feat at the start of his reign in the teams history, following on from William Lewis in 1906-07.Kohn-fident displaySalzburg owe a lot to their goalkeeper for keeping them in the game for so long, as Kohn made key saves to give the hosts hope most notably in the opening 45 minutes to deny a Havertz header and keep Pierre-Emerick Aubameyang out.Kohn made eight saves over the course of the game Zion Johnson Jersey , as well as charging off his line in brave fashion to prevent other opportunities materialising for Chelsea.Whats next?Potter faces a reunion with his former team Brighton and Hove Albion in the Premier League on Saturday, before Chelsea bring their group-stage campaign to a close against Dinamo Zagreb next Wednesday, when Salzburg face Milan at San Siro.