Juventus made a splash in the January transfer window when they snatched hot prospect Dusan Vlahovic and Switzerland midfielder Denis Zakaria, but their arrival has yet to provide the hoped-for boost ahead of Tuesday's Champions League visit to Villarreal.

Massimiliano Allegri's side travel to Spain as the only Italian side with a realistic hope of making the last eight after Inter Milan were beaten 2-0 at the San Siro by Liverpool on Wednesday.

However they go into the first leg of their last 16 tie in unsure form, with results and above all performances that have left fans unsatisfied with Allegri's first season back in black and white.

Vlahovic arrived at Juve to great fanfare after joining from Fiorentina for an initial fee of 70 million euros ($80.2 million), with Zakaria arriving three days later on deadline day.

Thrown straight in at the head of the Juve attack, with Alvaro Morata accommodating by shifting to a wide position, Serbia striker Vlahovic got off to a blistering start to life in Turin with a goal just 12 minutes into his debut against Verona.

But in the three matches since has shown some growing pains.

He struggled to make a mark at Atalanta last weekend, when Danilo saved Juve from what would have been a damaging defeat with a stoppage time header, and was kept almost anonymous by the impressive Bremer in his new team's 1-1 derby draw with Torino on Friday.

Allegri substituted Vlahovic with a quarter of an hour remaining against Torino and his team in need of a goal to consolidate their position in Serie A's Champions League places.

"At Fiorentina he played one match a week and now it's a game every three days... it's part of his development," said Allegri.

"He needs to get used to playing every three days, and do it using his technique and not just his strength. Otherwise he won't be able to physically handle playing playing 95 minutes twice a week."

After an atrocious start to the season, which also saw last season's top scorer Cristiano Ronaldo leave for Manchester United, Juve have been slowly creeping up the Serie A table despite some rag-tag performances.

Fans hoped the signings of Zakaria and in particular Vlahovic would add another dimension to a team which has scored just 38 times in their 26 league matches and was struggling to get goals even before Federico Chiesa was ruled out for seven months in January.

Only Torino have scored fewer in the top half of Serie A and they sit 10th, having been without Italy forward Andrea Belotti for much of the season.

However since being hit with the double whammy of being defeated at Chelsea in late November and then losing at home to Atalanta just a few days later Juve's only subsequent defeat has come in the Italian Super Cup.

They are on a run of 12 unbeaten in Serie A and have one of the league's stingiest defences, and eventually topped their Champions League group despite their embarrassment at Stamford Bridge.

The question now is whether Allegri can get a recognisable tune from a talented squad bolstered by a contender for Italy's 'Capocannoniere' top scorer award.