Celtic manager Martin O'Neill would have learned a lot from Thursday night's 4-1 defeat to Benfica in the Europa League, not least that a number of his players aren't ready to play on the biggest stage in Europe.

The likes of Dane Murray, Viljami Sinisaslo and Sebastian Tounekti really struggled for Celtic in the loss to Marco Silva's men, with a poor first half ultimately ending the match as a contest.

The Hoops improved in the second half but the damage had already been done, even though Camilo Duran did get on the score-sheet for the visitors to give them some hope of getting back into the game.

The performance and result will have given O'Neill plenty to ponder ahead of the important Scottish Premiership fixture at home to Hearts on Sunday, where the Hoops need to pick up the three points to stave off the increasing threat of Derek McInnes' Rangers side behind them.

The Northern Irishman will have some easy selection decisions for the visit of the Jambos, but there are some players who did give him something to think about in Portugal too.

Celtic did look better in midfield when Alex Oxlade-Chamberlain was introduced alongside captain Callum McGregor, while Jota could be an option too, having been ineligible to face Benfica.

Celtic under O'Neill this season:

• 13 Matches
• 8 Wins
• 0 Draws
• 5 Losses
• 26 goals scored
• 19 goals conceded

One player who did seriously force his way into O'Neill's thinking for the clash with Hearts was Haissem Hassan, who was arguably the club's best performer on the night, alongside Duran.

67 Hail Hail awarded him a 7/10 rating for his display against Marco Silva's men, even though he only played the second 45 minutes of the match.

Hassan Should be Starting Every Game Now

Considering he could end up costing the club £9m, it is a bit of a surprise that the Egypt international has only made five starts for the club so far, and has been a substitute in their previous four matches.

O'Neill has instead looked to the 24-year-old to make an impact from the bench, and he certainly did that in Lisbon on Thursday night.

The forward replaced the disappointing Kasper Hogh at half-time and Celtic instantly improved as an attacking force as a result.

Unlike Tounekti before him, the African winger looked to immediately cause problems for his full-back, and it was he who ended up setting up Duran for his goal in the 63rd minute.

Given the running he did and the issues he caused for a defence used to be in the Champions League, Hassan should have ensured he is one of the first names on O'Neill's team-sheet going forward.

It is a no-brainer decision for the 74-year-old manager, given Tounekti is struggling and coming under scrutiny from the fanbase, and Hogh isn't delivering in terms of goals either.

Hassan is proving he can make a difference and can create chances for his teammates, and that could be vital for a Celtic side that need to step things up both domestically and in Europe in the coming weeks.