THINGS YOU MISSED: Sanchez accidentally sits Solskjaer seat after being subbed

Manchester United managed to see off a resilient Reading side at Old Trafford to advance to the next round of the FA Cup while Burnley required a late Chris Wood penalty to see off League One opposition Barnsley.

Elsewhere, Brighton thumped Bournemouth on their own patch and West Ham eased past Birmingham.

Here, Sportsmail runs you through all the things you might have missed from the early action in the FA Cup.

Get out my seat, Sanchez!

Alexis Sanchez had to be reminded who the boss was after accidentally taking Ole Gunnar Solskjaer's seat.

The Chilean appeared to pick up an injury in the second half and had to be substituted off with fears he had aggravated the hamstring problem that kept him sidelined for almost six weeks.

Sanchez took his seat on the bench but was swiftly ejected from it after realising it was Solksjaer's. The United boss saw the funny side and patted him on the back as he moved to another seat.

Pellegrini and Arnautovic argue on the touchline

Manuel Pellegrini and Marko Arnautovic appeared to clash on the touchline after the latter was substituted on Saturday afternoon.

The striker had opened the scoring early on against Birmingham but was taken off and replaced by Andy Carroll in the 20th minute.

The fiery Austrian clearly didn't want to come off and got embroiled in a heated exchange with his boss Pellegrini on the touchline before heading straight down the tunnel.

It is reported that the former Stoke man was struggling with a back problem and Pellegrini did not want to take any risks with his main striker.

Gaffer in the building

Sir Alex Ferguson was in the stands on Saturday to watch Manchester United beat Reading in their FA Cup third-round clash.

And the Scotsman would have been pleased with what he saw as Ole Gunnar Solskjaer continued his winning run since taking over on as interim boss.

Solskjaer has continually said he is heavily influenced by Ferguson, who is believed to have had a say in his appointment, and it certainly seems as if it was a good decision to hire the Norwegian with United winning their fifth consecutive victory sine he's come in.

Mata's FA Cup run continues

Play Juan Mata in the FA Cup and he will deliver something significant.

The Spaniard just seems to love playing in the competition and continued his fine form in it on Saturday with another goal - he opened the scoring from the spot.

Mata, who has won it two times in his career, has now been directly involved in 21 goals in 24 starts in the FA Cup (10 goals, 11 assists).

Romelu Lukaku is another who seems to shine in the FA Cup, scoring 13 in his previous 14 appearances.

Knockaert returns to form

Brighton forward Anthony Knockaert returned to form on Saturday to help them defeat Bournemouth in their third-round tie.

The Frenchman has struggled this season but got on the scoresheet and set up a goal as Brighton ran out 3-1 winners at the Vitality Stadium.

It was the first time Knockaert had scored and assisted in the same match since December 2016 vs Birmingham.

Rashford takes a tumble

Marcus Rashford slipped over as he tried to keep the ball in play during the second half of Saturday's match.

The England forward, who is currently in hot form, was sent clear through but went too far around the goalkeeper and then went for a tumble.

Fortunately for United, Rashford did not injure himself in the process and managed to crack a smile at his own misfortune afterwards.