PARIS, Feb 17 — Four-time major winner Kim Clijsters makes a second career comeback in Dubai this week where the WTA will also experiment with coaching from the stands.

Not to be outdone, the ATP trials electronic line calling on clay courts for the first time.

AFP Sport looks at five talking points in tennis this week:

Clijsters ready for second comeback — Four-time Grand Slam champion Kim Clijsters revealed that a persistent inner feeling and advice from her husband served as the key to her WTA return at the Dubai Championships.

"It was a feeling that I had inside for a little while,” the 36-year-old mother-of-three said.

"Once in a while that feeling would go away when I was home with the (three) kids. A couple times it would come back. It got stronger and stronger.”

The Belgian has been handed a tough first round assignment against last month’s Australian Open finalist Garbine Muguruza for her first match since the 2012 US Open on Monday.

Clijsters retired initially in 2007 to marry and have her first child, returned in 2009 winning three of her four majors.

Electronic reviews make mark in Rio — Fourteen years after the electronic review challenge was introduced, the system debuts on clay for the first time in Rio from today.

The challenge system was first introduced on the ATP Tour in 2006 on the hard courts of Miami and has since been used on all surfaces with the exception of clay where the protocol of allowing players to ask chair umpires to check ball marks has been maintained.

Only show courts in Rio will have the system therefore there will be no limit to the number of challenges players are able to make to maintain consistency for those on outside courts where standard ball mark inspection will still apply.

Sending the right signals — It famously got Serena Williams into hot water at the 2018 US Open final, but now the WTA will sanction a trial of allowing coaches to signal to players at the Dubai tournament. 

At the moment, WTA tour players can summon their coaches into court during changeovers and only once in a set.

However, it’s not allowed at the four Grand Slams or at all on the ATP Tour.

"I am a big advocate for on-court coaching as I believe it is great for the show and will help people behind their TV or computer understand our sport and know players’ personalities better,” said Patrick Mouratoglou, the coach of Serena Williams and whose prompting from the stands sparked the American’s infamous New York meltdown.

Borg begins new family era — Leo Borg, the 16-year-old son of Swedish legend and 11-time Grand Slam champion Bjorn, makes his pro debut this week at the second-tier Challenger event in Bergamo, Italy.

Borg, who is ranked 98 in the world junior rankings, begins against a qualifier in the 46,000-euro Bergamo event. If he gets through that, he’d come up against grizzled 30-year-old Argentine Marco Trungelliti.

Ruud awakening for Norway — Casper Ruud became the first Norwegian to win an ATP title on Sunday after seeing off Pedro Sousa 6-1, 6-4 in the final at Buenos Aires.

The win will move 21-year-old Ruud up to 34 in the world rankings, which will be his best ever placing—and better than the career-high achieved by his father and coach Christian who was 39 in the world in 1995, three years before his son was born.

Latest rankings

ATP

1.            Novak Djokovic (SRB) 9,720 pts

2.            Rafael Nadal (ESP) 9,395

3.            Roger Federer (SUI) 7,130

4.            Dominic Thiem (AUT) 7,045

5.            Daniil Medvedev (RUS) 5,890

6.            Stefanos Tsitsipas (GRE) 4,745

7.            Alexander Zverev (GER) 3,885

8.            Matteo Berrettini (ITA) 2,860

9.            Gael Monfils (FRA) 2,860

10.         David Goffin (BEL) 2,600

11.         Fabio Fognini (ITA) 2,400

12.         Roberto Bautista (ESP) 2,360

13.         Diego Schwartzman (ARG) 2,265 (+1)

14.         Andrey Rublev (RUS) 2,219 (+1)

15.         Denis Shapovalov (CAN) 2,075 (+1)

16.         Stan Wawrinka (SUI) 2,060 (-3)

17.         Karen Khachanov (RUS) 2,040

18.         Felix Auger-Aliassime (CAN) 1,921 (+3)

19.         John Isner (USA) 1,850 (-1)

20.         Benoit Paire (FRA) 1,738 (-1)

WTA

1.            Ashleigh Barty (AUS) 8,367 pts

2.            Simona Halep (ROU) 5,796

3.            Karolina Pliskova (CZE) 5,290

4.            Belinda Bencic (SUI) 4,720 (+1)

5.            Bianca Andreescu (CAN) 4,665 (+1)

6.            Elina Svitolina (UKR) 4,650 (-2)

7.            Sofia Kenin (USA) 4,495

8.            Kiki Bertens (NED) 4,335

9.            Serena Williams (USA) 3,915

10.         Naomi Osaka (JPN) 3,626

11.         Petra Kvitova (CZE) 3,566

12.         Madison Keys (USA) 2,962

13.         Aryna Sabalenka (BLR) 2,820

14.         Johanna Konta (GBR) 2,753

15.         Petra Martic (CRO) 2,586

16.         Garbine Muguruza (ESP) 2,527

17.         Marketa Vondrousova (CZE) 2,431

18.         Alison Riske (USA) 2,360

19.         Elena Rybakina (KAZ) 2,141 (+6)

20.         Angelique Kerber (GER) 2,090 — AFP