Neymar frustrating for Barcelona while Messi stars

With Lionel Messi firing on all cylinders again, Barcelona's Champions League challenge is very much alive but coach Gerardo Martino would be much happier if marquee signing Neymar was not on such patchy form.

Messi scored his eighth goal in five appearances in the latest edition of Europe's elite club competition in Wednesday's 2-1 win at home to Manchester City, which sent the Spanish champions through to the quarter-finals for the seventh straight season, 4-1 on aggregate.

It was a typically brilliant piece of skill from the Argentina forward as he dinked the ball over City goalkeeper Joe Hart in the 67th minute, his 28th goal of the season during which he has spent two months on the sidelines with a thigh injury.

Neymar started the last 16, second leg match at the Nou Camp instead of Alexis Sanchez and Pedro, who have both been on good form this term, but the Brazil forward squandered the chances that came his way and turned in a generally disappointing performance before making way for Alexis 10 minutes from time.

Out for several weeks in late January and early February with a twisted ankle, Neymar has only scored once for Barca since the turn of the year, the sixth goal in a 6-0 La Liga drubbing of minnows Rayo Vallecano.

It is hard not to think that the controversy surrounding his move from Santos in the close season, which has prompted charges of misappropriation of funds and tax evasion, and the pressure of playing for one of the world's richest clubs are having some effect on the 22-year-old.

It must also be perplexing for Martino that Neymar can head off on international duty and net a hat-trick in a friendly against South Africa this month but fail to step up when he pulls on the Barca shirt.

Martino defended Neymar at his post-match news conference on Wednesday and noted the player was still working his way back after the ankle injury.

"Neymar made a big contribution to the team and did some great work helping in defence," the Argentine told reporters.

"In the first half he had two good chances and the process of rejoining the team means he still can't manage the 90 minutes."

However, Barca did not buy Neymar to help out in defence and they will be expecting more from him as the season enters a crucial phase with the club still alive in all three competitions they are contesting.

Chasing a fifth La Liga title in six years, they are four points behind La Liga leaders Real Madrid in third and play at their arch rivals on March 23.

The Champions League quarter-finals, where they could be drawn against Real, are at the start of April and they meet them again in the final of the King's Cup on April 16.

Barca slipped to third in La Liga behind Atletico Madrid last weekend after a shock 1-0 defeat at Real Valladolid and anything other than a win at home to Osasuna on Sunday could see them drop out of the domestic title race.

There have been plenty of doubts about their style of play this season, in particular surrounding the defence, which has been vulnerable in the air from set-plays.

It has been a difficult first year in charge for Martino, who arrived with his own ideas and felt that the team needed to have more in its armoury than just their typical short-passing football.

He has tried several different styles looking to make the team more direct, including interchanging long and short balls and switching possession from different wings.

However, a number of lacklustre displays have added to the sense that Barca are a club in decline after a spectacular run of success under former coach Pep Guardiola.

"The team has had ups and downs and we are coming to this point in the season with less calm than we wanted," Martino said. "In Valladolid we were lacking in football not in intensity.

"In the same way that we put on a poor show there, today we turned that around."