Despite winning four of their first five Premier League games, things haven’t been plain sailing for Ronald Koeman since taking over at Everton in the summer.

The Dutchman replaced the sacked Roberto Martinez in the summer after a disappointing campaign last time out, with the brief to get the Toffees back up near the European spots.

And, 13 games in, they are there or thereabouts, but their recent form suggests that they might not be there for much longer.

They have won just one of their last eight Premier League games, and their poor performance away at Southampton on Sunday was indicative of a side low on confidence and struggling to break a rut.

This is all after a start to the season which had many Everton fans optimistic about the campaign ahead, as they won four of their opening five matches and sat second in the league behind Manchester City on September 17.

Koeman knows that they must improve in the next few games and, with January fast approaching, many are speculating on who the Dutchman could look to sign to bolster his squad so that they do finish in the top six come May.

One area that might need improving is the back four, so here is the dream Everton defence, including two key January targets…

RB – Seamus Coleman

Seamus Coleman cost Everton a mere £60,000 back in 2009, and it’s fair to say that the Toffees have got their money’s worth and more from the Republic of Ireland international.

The 28-year-old made his breakthrough at Goodison Park in the 2010/11 campaign, a few months after being on loan at Blackpool, and has since gone on to be a regular feature in the Everton backline, appearing 172 times in the last five seasons.

Coleman continues to shine down the right-hand-side for the Toffees, both defensively and offensively, and at 28 he should be in or entering the peak of his career, which should excite Everton fans.

CB – Niklas Sule

https://www.youtube.com/watch?v=ioArRpXVHhs&t=3s

He has been a brilliant servant for Everton, but you sense that time is beginning to get the better of Phil Jagielka.

The centre-back has been excellent for the club since moving to Goodison Park in 2007, and has deservedly been recognised for his fine displays with 40 England caps.

However, as this season and indeed parts of last season showed, he’s not as good a defender as he once was, and at 34 it’s unlikely that he’ll regain that form.

Thus, Koeman should be looking to freshen up his backline, and Hoffenheim defender Niklas Sule could be the perfect long-term replacement for Jagielka.

At 21, the German international has already accumulated 90 appearances for the Bundesliga club, and also earned his first cap for the national team earlier this year.

He’s a defender whose stock is rising, and given Everton have been linked with him, Koeman must attempt to bring him to Merseyside in January.

CB – Ashley Williams

Wales’ Ashley Williams has been arguably one of the best centre-backs in the Premier League over recent seasons, so it was seen as a big scalp when Everton pinched him from Swansea in the summer.

The Toffees were hopeless defensively last season, conceding 66 goals in all competitions, but they immediately looked more solid earlier on this season following Williams’ arrival.

Although they have struggled in recent weeks, the 32-year-old has easily got a couple more years at the heart of the Everton backline, and would certainly complement the young Sule if he made the move to Goodison Park.

LB – Sead Kolasinac

Similarly to Jagielka, Koeman must be thinking about a long-term replacement for Leighton Baines.

The 31-year-old, like Jagielka, joined the Toffees back in 2007, and has been a mainstay of the side ever since, except last season, where he made just 18 Premier League appearances.

Injury may have interrupted his last campaign, but you sense that he’s not the same player he was a few years ago, and has subsequently fallen out of the England reckoning having not appeared for the Three Lions since March 2015.

Consequently, Koeman may consider reinforcing his left-back department, and one man he should certainly take a look at is 23-year-old Sead Kolasinac.

The Bosnia and Herzegovinian international has been a regular at German side Schalke since moving there in 2012, and his versatility has seen him receive praise from many quarters while in Germany.

However, his adeptness at full-back is something that is sure to interest Koeman, who could face competition from Chelsea and Tottenham for his signature.