Celtic's Georgios Samaras runs with a ball during a team training session ahead of their Champions League match against Juventus at their training complex in Lennoxtown near Glasgow, Scotland, Monday. — Reuters VALENCIA — Valencia has to find a way to both breach Paris Saint-Germain's rock-solid defense and keep top scorer Zlatan Ibrahimovic quiet when they meet in the last 16 of the Champions League Tuesday. PSG has not been beaten since losing 2-1 away to Nice on Dec. 1, winning 11 and drawing one of its past 12 matches in all competitions and conceding only five goals during that run. Ibrahimovic came off the bench to notch his 23rd goal of the season in Friday's 3-1 home win against Bastia — including 21 in just 21 league games. Things have vastly improved at PSG since the turn of the year, and it has pulled ahead of its title rivals Lyon and Marseille. Now it must assert itself in Europe. In Scotland, after beating Barcelona in one of the biggest shocks of the group stage, the visit of Juventus holds no fears for Celtic ahead of their last-16 match Tuesday. AC Milan and Manchester United have also slipped to Champions League losses at the intimidating Celtic Park since 2006, so the Italian champion and current Serie A leader has been warned. "I think playing against arguably the best team in the world (Barcelona) is a tougher game on paper but I think we're playing for something a lot bigger," Celtic playmaker Kris Commons said. "The prize at the end of it is bigger. "It's a luxury tie for us but we know we are more than capable of winning the match. We fancy ourselves over the two legs — we're quietly confident." Celtic relied on set pieces and counterattacks to not only beat Barcelona 2-1 at home — reducing pop star and loyal fan Rod Stewart to tears in the process — but also come within a stoppage-time goal from Jordi Alba of earning a draw at Camp Nou in group play. The same pragmatic approach is likely to be utilized against Juventus, which is expected to dominate possession in both legs — especially with classy Italy midfielder Andrea Pirlo recovered from a thigh strain that he sustained on international duty. Juventus warmed up for the match with a 2-0 win over Fiorentina Saturday, putting the team's league campaign back on track after struggling somewhat in January. "We had a lapse a few weeks ago but we've bounced back great," defender Federico Peluso said. "That's our strength. Now we've got to face Celtic with the same spirit. "We're aware of our strength. After all, if we've reached the last 16 of the Champions League, it's not by chance." However, Juve probably won't have come across an atmosphere quite like the one it will experience Tuesday. Gerard Pique and Xavi Hernandez were two of the Barcelona players to have been taken aback about the noise levels coming from Celtic's supporters in the 60,000-seat stadium during the Nov. 7 game. "No words to describe the atmosphere at Celtic Park," Pique said on Twitter soon after the match. Barcelona coach Tito Vilanova added he "had never seen anything like it." Commons said the backing can't fail to help. "Juventus are no mugs, it's not like they've never seen this sort of atmosphere before," he said. "They get paid incredible wages to deal with that and play in these arenas but the atmosphere gives us a lift and increases our game.” — Agencies