It was hardly the obvious place for Jose Mourinho to have an epiphany about his best Manchester United line-up, but that September night at Sixfields in Northampton may have saved their season.

After three damaging defeats on the bounce, the last thing Mourinho and United needed was a tricky EFL Cup draw against a voracious League One side rarely beaten in their own backyard.

To safeguard against an upset, Mourinho decided to partner Ander Herrera and Michael Carrick in midfield and in so doing stumbled upon a winning formula that continues to serve him well.

Ander Herrera scores in the EFL Cup at Northampton, the match that persuaded Jose Mourinho to offer him more regular football in the Manchester United team

Herrera celebrates with Marcus Rashford after United secured safe passage at Northampton

Since then, Herrera has been a regular fixture in Jose Mourinho's United team

When he started on the bench for four of United's first Premier League matches, Herrera must have thought Mourinho was going to be just as unappreciative of his talents as his predecessor Louis van Gaal.

In two seasons at Old Trafford, the quiet and unassuming Spaniard had only been afforded occasional opportunities to let his feet do the talking and this campaign just promised more sitting on his backside in the dug-out.

But a Herrera goal and assist steered United past Northampton and when he started and helped United to a 4-1 victory over defending champions Leicester City the following Saturday, it was clear things had changed.

Since then, Herrera has been an indispensable part of Mourinho's team. In tandem with Carrick, he has enabled £89million signing Paul Pogba to be liberated and brought greater balance to United's midfield.

Louis van Gaal never fully appreciated Herrera's talents during his two years in charge

Mourinho has been more willing to play Herrera on a regular basis this season

ANDER HERRERA STATS IN THE PREMIER LEAGUE 2014-15 2015-16 2016-17 Appearances 26 27 15 Minutes played 1868 1532 1187 Average minutes per app. 72 57 79 Goals 6 3 0 Total shots 37 24 20 Assists 4 2 2 Chances created 26 21 16 Passes 1554 1097 1016 Successful passes 1386 922 888 Passing accuracy % 89.2 84.1 87.4 Tackles 73 56 40 Interceptions 51 24 47 Yellow cards 6 4 2 Red cards 0 0 1 Average shots per game 1.8 1.4 1.5 Average passes per game 74.9 64.4 77 Successful passes per game 66.8 54.2 67.3 Minutes per chance created 71.8 73 74.2 Tackles per game 3.5 3.3 3 Interceptions per game 2.5 1.4 3.6 Source: Opta

This heat map from United's 1-1 draw at Everton shows how Herrera covers the whole field

The midfielder put in another all-action performance against Sunderland on Boxing Day

In almost every facet of his game, Herrera has shown improvement this season and all that was required was the consistent faith of a manager.

One stat in particular illustrates the work ethic of Herrera that is often overlooked - he has made more interceptions this season (47) than any other midfielder in the Premier League.

His tally is one more than Chelsea's famously inexhaustible midfielder N'Golo Kante and all the more noteworthy when you consider that Herrera has reached his total in just 1,189 minutes of league football as opposed to Kante's 1,530.

The increased game time naturally gives a more positive slant to Herrera's numbers, but the average number of successful passes has risen from 54.2 per game last season to 67.3 this.

Herrera has registered more interceptions this season than Chelsea workhorse N'Golo Kante

Herrera makes a slide challenge on Sunderland striker Fabio Borini on Boxing Day

The United midfielder steers the ball away from Sunderland's Patrick van Aanholt

Herrera leaps to beat Everton's Idrissa Gueye to a header in the match at Goodison Park

The Spanish midfielder beats Tottenham's Heung-min Son to the ball at Old Trafford

Most interceptions in the Premier League 66 - Curtis Davies 54 - Winston Reid; Nacho Monreal 51 - Laurent Koscielny 47 - Papy Djilobodji; Ander Herrera 46 - Virgil van Dijk; N'Golo Kante 45 - Antonio Barragan; Ben Mee Advertisement

And despite a deep midfield role, Herrera has already contributed two Premier League assists - the same as in the whole of last season - and created 16 chances. In 2015-16, he created 21 chances in the whole campaign.

It cannot be a coincidence either that Herrera's regular presence in the United side has resulted in an unbeaten run of nine Premier League matches dating back to their 4-0 loss at Chelsea back on October 23.

Having rediscovered the knack of converting draws into victories, United have also won their last four in the league and will be strong favourites to make that five when they host Middlesbrough on New Year's Eve.

It has contributed to a feel-good factor at Old Trafford, particularly from Mourinho, as their early season troubles are left behind.